All calculators
927 free calculators in 17 categories. Type to narrow the list, or browse A–Z.
Concrete & masonry
Slabs, footings, posts and block walls.
- Concrete CalculatorSlabs, walls, footings, columns and steps: cubic yards, bag counts and cost.
- Concrete Block CalculatorBlocks, mortar and grout for a CMU wall, with openings deducted.
- Concrete Steps CalculatorConcrete and bags for solid steps.
- Sonotube & Post Hole CalculatorConcrete for tube forms, piers and fence posts.
- Brick CalculatorBricks and bags of mortar for walls and houses, by brick size.
- Retaining Wall CalculatorBlocks, caps, base gravel and drainage stone for a block retaining wall.
- Stone Wall CalculatorTons of wall stone from the wall face and your stone's coverage.
- Rebar CalculatorRebar for a slab: bars each way, 20 ft bars with laps, weight and ties.
- Concrete Weight CalculatorWeight of slabs and columns in pounds, tons and kilograms.
- Metal Weight CalculatorWeight of steel, aluminum and other metal plate, bar, pipe, tube and angle.
- Mortar CalculatorBags of mortar mix for brick and concrete block walls.
Landscaping
Gravel, soil, pavers, lawns and slopes for the yard.
- Gravel CalculatorTons and cubic yards of gravel for driveways, paths and bases.
- River Rock CalculatorTons, cubic yards and bags of river rock for beds, borders and dry creeks.
- Sand CalculatorSand for sandboxes, pavers, pool bases and leveling, in tons, yards and bags.
- Mulch CalculatorBags or cubic yards of mulch for beds of any shape.
- Compost CalculatorCompost for garden beds and lawn topdressing, in cubic yards and bags.
- Topsoil & Dirt CalculatorCubic yards of topsoil for lawns, beds and raised gardens.
- Paver CalculatorPavers, base gravel and sand for patios and walkways.
- Landscape Edging CalculatorFeet of edging, 20–50 ft kits and anchoring spikes for beds.
- Sod CalculatorSquare feet, pallets, slabs and rolls of sod for a new lawn.
- Grass Seed CalculatorPounds and bags of grass seed for a new lawn or overseeding, by grass type.
- Plant Spacing CalculatorPlants per bed, grid or staggered.
- Tree Height CalculatorTree height with a clinometer.
- Fertilizer CalculatorPounds and bags of lawn fertilizer from the N-P-K and nitrogen rate.
- Asphalt CalculatorTons of hot mix for driveways and paths, plus cold patch bags for repairs.
- Slope CalculatorPercent grade, degrees and drop for yards, drainage and ramps.
- Acreage CalculatorAcres, hectares and square feet of a lot or field, with the price per acre.
- Pond CalculatorPond gallons, liner and underlayment size, and pump GPH.
- Rainwater Harvesting CalculatorGallons of rain your roof can collect.
- Pool Volume CalculatorGallons in a rectangular, round or oval pool, and time to fill.
- Cubic Yard CalculatorAny area and depth in cubic yards, for any bulk material.
- Cubic Feet CalculatorCubic feet of boxes, rooms and cylinders, with yards, gallons and liters.
- Material Weight CalculatorWeight of gravel, sand, soil, asphalt, concrete or water in tons.
- Pool Salt CalculatorPounds and bags of salt to reach your target ppm, or water to drain.
- French Drain CalculatorGravel, perforated pipe and filter fabric for a French drain trench.
- Raised Bed Soil CalculatorSoil for raised garden beds in cubic feet, yards, liters and bags.
- Pool Chlorine CalculatorLiquid chlorine, cal-hypo, dichlor or trichlor to raise free chlorine to your target.
- Lawn Watering CalculatorMinutes to run your sprinklers and gallons per week for a lawn.
- Trench Volume CalculatorTrench volume with sloped sides, loose soil to haul and truck loads.
- Chicken Coop Size CalculatorCoop floor, run, roost and nest boxes for your hens, from university extension guides.
- Seed Starting Date CalculatorWhen to start seeds indoors and set out 34 vegetables from your last frost date.
- Growing Degree Days CalculatorAccumulated GDD from daily highs and lows, with corn stages.
- Egg Incubation CalendarHatch date, last turning day and candling days for chicken, duck, goose, turkey and quail eggs.
- Horse Weight CalculatorEstimate a horse’s weight from heart girth and body length, plus daily hay by percent of body weight.
- Stocking Rate CalculatorHow many animals a pasture carries, acres needed per animal unit and days of grazing, from forage yield and AUM.
- Hay Needed CalculatorTons and bales of hay for the winter for horses, cattle, sheep or goats, with feeding and storage waste and cost.
- Rain Garden Size CalculatorRain garden area from roof size, soil and depth, plus storm and drain-down check.
- Drip Irrigation CalculatorRun time, emitters, gallons per plant and zone size for a drip system.
- Soil Texture CalculatorUSDA soil texture class from percent sand, silt and clay, or a jar test.
- Sprinkler Spacing CalculatorSprinkler heads for your lawn, square or triangular layout, precipitation rate and run time.
- Downspout Count CalculatorHow many downspouts a roof needs from its area and the design rainfall.
- Culvert Size CalculatorCulvert pipe diameter for a driveway or farm crossing from area, runoff and rain.
- Driveway Grade CalculatorDriveway slope in percent and degrees, and whether a car clears the crest.
- Tree Spacing CalculatorDistance between trees, plants for a hedge, and rows and plants for a windbreak.
- Swale Capacity CalculatorFlow and velocity of a grass swale or ditch, checked against the grass velocity limit.
Walls, floors & roof
Paint, drywall, flooring, trim, insulation, roofing and gutters.
- Paint CalculatorGallons of paint for walls and ceilings, with doors, windows and coats.
- Drywall CalculatorSheets of drywall for walls and ceilings, 4×8 to 4×12.
- Tile CalculatorTiles and boxes for floors, walls and backsplashes, with grout joints and extra for cuts.
- Grout CalculatorPounds and bags of tile grout by tile size, joint and thickness.
- Caulk CalculatorFeet per tube and tubes of caulk for any joint size.
- Laminate Flooring CalculatorBoxes of laminate for any room, plus underlayment.
- Flooring CalculatorSquare feet and boxes of vinyl plank, laminate or hardwood, plus underlayment.
- Countertop CalculatorSquare feet of counters, islands and backsplash, slabs and cost.
- Epoxy CalculatorGallons of epoxy for floor coatings and table or river pours.
- Carpet CalculatorSquare yards of carpet and pad for rooms and stairs.
- Wallpaper CalculatorRolls of wallpaper for rooms and walls, with the pattern repeat.
- Board and Batten CalculatorBatten spacing and lumber for an accent wall, or boards for siding.
- Roof CalculatorSquares and bundles of shingles by roof pitch, plus underlayment.
- Metal Roofing CalculatorMetal roof panels and their cut length, squares and trim.
- Gutter CalculatorFeet of gutter, downspouts, elbows and hangers for every run.
- Siding CalculatorSquares of siding for walls and gables, doors and windows taken out.
- Roof Pitch CalculatorPitch, angle, grade and rafter length from rise and run.
- Rafter Length CalculatorCommon rafter length from run and pitch.
- Insulation CalculatorR-value by climate zone and bags or rolls for attics, floors and walls.
- Attic Ventilation CalculatorNet free vent area by the IRC.
- Egress Window CalculatorCheck IRC egress window size.
- Baseboard CalculatorLinear feet and 8, 12 or 16 ft pieces of baseboard for any room.
- Crown Molding Angle CalculatorMiter and bevel settings for crown.
- Square Footage CalculatorSquare feet, yards, acres and meters for any shape, with cost.
- Square Yards CalculatorSquare yards for rooms and areas of any shape, with the cost per square yard.
- Cost to Build a House CalculatorHouse price estimate from its size and 2025 Census cost per square foot.
- Spray Foam CalculatorBoard feet of open- or closed-cell spray foam and kits, by thickness or R-value.
- Stucco CalculatorBags of base and finish coat stucco for your walls, three or two coats.
- Shiplap CalculatorBoards, linear feet and rows of shiplap for walls and ceilings.
- Rough Opening CalculatorRough opening for a door, window or patio door from the maker's allowance.
- Wainscoting Calculator4x8 sheets or boards, cap rail, baseboard and paint area for wainscoting.
- Room Illuminance CalculatorLumens needed to light a room to a foot-candle or lux level, with CU and LLF.
Wood, deck & fence
Decks, fences, stairs, wall framing and lumber.
- Deck CalculatorDeck boards by width, gap and length, plus screws or hidden clips.
- Deck Joist CalculatorJoist count and hangers, with a span check against IRC R507.6.
- Pergola CalculatorPosts, beams, rafters and purlins for a pergola, with lengths.
- Deck Beam Span CalculatorMaximum deck beam span between posts from IRC Table R507.5.
- Fence CalculatorPickets or panels, posts, rails and post concrete for any fence.
- Board Foot CalculatorBoard feet and cost for a list of lumber.
- Firewood Cord CalculatorCords of wood in a stack.
- Lumber CalculatorHow many boards to buy for your cut list, with the cutting layout.
- Linear Feet CalculatorLinear feet to square feet and back for boards, decking and shiplap.
- Stair CalculatorSteps, riser height, treads and stringer length from the total rise.
- Ramp CalculatorWheelchair ramp length, landings and handrails per the ADA.
- Wall Framing CalculatorStuds, precut stud length, plates and headers for framed walls.
- Plywood CalculatorSheets of plywood or OSB for wall, roof and floor sheathing.
- Cabinet Door CalculatorOverlay or inset cabinet door size from the opening, to 1/16 in.
- Feet and Inches CalculatorAdd, subtract, multiply and divide lengths with fractions of an inch.
- Scale CalculatorDrawing to real size and back at 1/4 in = 1 ft, 1:100 or any scale.
- Floor Joist Span CalculatorMaximum floor joist span by wood, grade, size and spacing from IRC R502.3.1.
- Baluster Spacing CalculatorHow many balusters and the exact equal gap under the 4-inch rule.
- Ladder Angle & Length CalculatorLadder length and base distance by the OSHA 4-to-1 rule, or check your angle.
- Deck Footing CalculatorFooting size and concrete for deck posts from the load, soil and IRC R507.3.
- Stud Layout CalculatorStuds, king and jack studs, cripples, headers and plates for one wall.
Heating, cooling & electrical
Air conditioning, water heaters, heating cost, pipes and wiring.
- BTU CalculatorAir conditioner size for a room, from the ENERGY STAR table.
- Water Heater Size CalculatorTank first-hour rating or tankless flow and temperature rise.
- Heating Cost CalculatorYearly heating cost with gas, propane, oil, electric or a heat pump.
- Heat Loss CalculatorBTU/h lost through walls, windows and roof.
- Furnace Size CalculatorYour home's heat loss and the furnace BTU it needs, by insulation and climate.
- CFM CalculatorBathroom fan and range hood size in CFM, per HVI guidelines.
- Duct Size CalculatorAir velocity and round duct size.
- Ceiling Fan Size CalculatorFan blade span by room size from the ENERGY STAR chart, and how low to hang it.
- Pipe Volume CalculatorGallons of water in copper, PEX or PVC pipe by size and length.
- GPM CalculatorWater flow in gallons per minute by bucket test or pipe size.
- Tank Volume CalculatorGallons in round or rectangular tanks, full or partly full.
- Pipe Size CalculatorWater pipe size for a flow, with the water speed in each size.
- Pipe Flow Velocity CalculatorGPM to feet per second.
- Friction Loss CalculatorPressure loss in water pipe, in psi and feet of head.
- Head Pressure CalculatorFeet of water to psi and back.
- Wire Size CalculatorWire gauge by amps, length and voltage drop, per NEC 310.16.
- Conduit Fill CalculatorConduit fill and the smallest EMT or PVC size, per NEC Chapter 9.
- Box Fill CalculatorCubic inches of wires and devices in an electrical box, per NEC 314.16.
- Breaker Size CalculatorCircuit breaker size for a load, and the wire gauge for it.
- Voltage Drop CalculatorVoltage drop in volts and percent for any wire size and run.
- Wire Resistance CalculatorResistance of copper and aluminum wire.
- Watts to Amps CalculatorWatts, amps or volts from the other two, plus the breaker for the load.
- Three-Phase Power CalculatorkW, kVA and amps for 3-phase loads.
- Transformer CalculatorTurns ratio, voltage and current.
- Ohm's Law CalculatorVolts, amps, ohms and watts from any two known values.
- Series and Parallel CalculatorResistors and capacitors in series or parallel.
- Voltage Divider CalculatorOutput voltage of two resistors.
- RC Time Constant CalculatorCapacitor charge and discharge time.
- Resonant Frequency CalculatorLC resonance and reactance.
- Resistor Color Code CalculatorBand colors to ohms, for 3 to 6 bands.
- LED Resistor CalculatorCurrent-limiting resistor for LEDs.
- Generator Size CalculatorRunning and starting watts your generator must supply.
- Electricity Cost CalculatorCost to run any appliance per day, month and year, from watts and your rate.
- Lumens to Watts CalculatorLED lumens for an incandescent bulb.
- Solar Panel CalculatorSystem size in kW and number of panels from your kWh use and sun hours.
- Battery Runtime CalculatorHow long a battery or UPS runs a load, or the battery size you need.
- Water Softener Size CalculatorGrains of softener capacity from household, water use and hardness.
- Capacitor CalculatorCapacitor codes like 104K, energy stored and parallel-plate capacitance.
- EV Charger Circuit CalculatorBreaker and wire size for a Level 2 EV charger, per the NEC 125% rule.
- 555 Timer CalculatorFrequency, duty cycle and pulse length of a 555 astable or monostable.
- Air Purifier Size CalculatorCADR needed for a room, the room a CADR can handle, and air changes per hour.
- SEER CalculatorSEER to SEER2, yearly cooling cost and savings, and DOE minimums by region.
- Ventilation Rate CalculatorWhole-house ventilation in CFM from floor area and bedrooms, per ASHRAE 62.2.
- Propane CalculatorGallons in a tank from the gauge, pounds to gallons, and days a tank lasts.
- Pipe Slope CalculatorMinimum drain pipe slope and fall by pipe size, from the IPC and UPC.
- Expansion Tank CalculatorThermal expansion tank size for a water heater or a closed heating system.
- Dehumidifier Size CalculatorPints per day by room size and dampness, and old versus new capacity ratings.
- Dryer Vent Length CalculatorDryer duct length with elbows against the 35 ft IRC limit.
- Humidifier Size CalculatorGallons per day a humidifier must add, from floor area, ceiling height and tightness.
- Water Heater Cost CalculatorYearly cost: heat pump vs electric vs gas vs propane.
- Conduit Bending CalculatorOffset, 90-degree stub-up and 3-bend saddle marks for EMT and rigid conduit.
- Septic Tank Size CalculatorMinimum septic tank gallons by bedrooms and how often to pump.
- Pressure Tank Drawdown CalculatorUsable water per cycle of a well pressure tank, and the tank size a pump needs.
- Sump Pump Size CalculatorPump gpm and head from basin size, water rise, lift and discharge pipe.
- Radiant Floor Tubing CalculatorPEX length, loops, flow and head loss for a hydronic radiant floor.
- UPS Sizing CalculatorVA and watts for a UPS, load check and runtime estimate.
- LED Strip Power CalculatorPower supply, current and voltage drop for 12 V and 24 V strips.
- PoE Power Budget CalculatorSwitch PoE budget by class for cameras, access points and phones.
- Standby Power Cost CalculatorYearly kWh, dollars and CO2 of vampire load from your devices’ standby watts.
- LED Savings CalculatorYearly saving, payback and lifetime savings of switching bulbs to LED.
- Shower Water Cost CalculatorYearly water and heating cost of showers, and what a 2.0 gpm WaterSense head saves.
- Window Replacement Payback CalculatorYears to pay back new windows from U-factor, climate, fuel price and cost.
- Thermostat Setback CalculatorYearly saving from turning the thermostat down at night or when away.
- Home Battery Sizing CalculatorBackup battery kWh, inverter size and units from your critical loads and days of backup.
Time & date
Age, days between dates, adding time and hours worked.
- Age CalculatorExact age in years, months and days, and the countdown to your next birthday.
- Date CalculatorDays and business days between dates, or add and subtract days.
- Business Days CalculatorWorkdays between dates, without federal holidays.
- Days From Today CalculatorThe date 30, 60, 90 or any number of days from today or ago.
- Time CalculatorAdd and subtract hours and minutes, or time on the clock.
- Hours CalculatorHours worked between two times, with breaks and pay.
- Time Card CalculatorWeekly hours from each day's times, overtime over 40 and pay.
- Time to Decimal CalculatorHours and minutes to decimal hours and back.
- Countdown CalculatorDays until Christmas, a holiday or any date, with a live countdown.
- Time Zone ConverterA time in one zone in another — Eastern, Pacific, world cities.
- Day of the Year CalculatorToday's date, day of the year, week number and days left.
- Day of the Week CalculatorWhat day of the week any date was or will be.
- Week Number CalculatorISO week number of any date, and its dates.
- Julian Date CalculatorYYDDD date code and astronomical Julian Date.
- Sunrise Sunset CalculatorSunrise, sunset and day length for any date.
- Daylight Saving Time CalculatorWhen US clocks change, any year.
- Military Time Converter24-hour military time to AM/PM and back, with a chart.
- Unix Timestamp ConverterEpoch time in seconds or milliseconds to a date and back.
- Leap Year CalculatorIs it a leap year? The next and previous ones.
- Easter Date CalculatorWestern and Orthodox Easter by year.
- CalendarAny year's calendar with US federal holidays, ready to print.
- Moon Phase CalculatorMoon phase, illumination and next full moon.
- Sun Angle CalculatorSun elevation, azimuth and shadow length for any place and time.
- Meeting Time PlannerBest meeting time across 2 to 4 time zones, with shared working hours.
- Life in Weeks CalculatorWeeks lived, weeks left and the Saturdays and summers ahead.
- Jet Lag CalculatorDays to adjust after crossing time zones.
- Nth Weekday of the Month Calculator4th Thursday, last Monday, US holiday dates by rule.
- Hebrew Date ConverterGregorian to Hebrew date and back, with Jewish holidays.
- Hijri Date ConverterGregorian to Islamic date and back, vs Umm al-Qura.
- Season Start CalculatorExact time of equinoxes and solstices, season lengths.
- Daylight Saving Time Dates by RegionClock changes in the US, Europe, Australia, New Zealand.
- Friday the 13th CalculatorEvery Friday the 13th, or the years your date hits a weekday.
- Screen Time Life CalculatorHours and years of screen time over a lifetime.
Math
Percentages, fractions, ratios and everyday math.
- Percentage CalculatorPercent of a number, what percent, percent change and more, with steps.
- Fraction CalculatorAdd, subtract, multiply and divide fractions and mixed numbers.
- Ratio CalculatorSimplify a ratio or scale it to find the missing number.
- Aspect Ratio CalculatorRatio of any size, or resize at a ratio.
- Proportion CalculatorSolve A/B = C/D for the missing value, with the steps.
- LCM and GCF CalculatorLeast common multiple and greatest common factor, with prime factors.
- Factor CalculatorAll factors, prime factorization and whether a number is prime.
- Average CalculatorMean, median, mode, range and standard deviation of a list.
- Weighted Average CalculatorWeighted mean of values and their weights.
- Geometric Mean CalculatorGeometric, harmonic and arithmetic mean.
- Rounding CalculatorRound to decimal places, the nearest 10, 100 or 1,000, or sig figs.
- Square Root CalculatorSquare, cube and nth roots, simplified radicals and powers.
- Simplify Radicals CalculatorSquare and cube roots in simplest form.
- Random Number GeneratorRandom whole numbers in any range, with or without repeats.
- Area CalculatorArea of rectangles, triangles, circles, trapezoids and more.
- Volume CalculatorVolume of boxes, cylinders, spheres, cones and pyramids.
- Binary ConverterBinary, decimal, hex and octal, exact for big numbers.
- Number Base ConverterAny base from 2 to 36.
- Scientific CalculatorTrig in degrees or radians, logs, powers, roots and factorials.
- Exponent CalculatorPowers with negative and fractional exponents, or the missing base.
- Log CalculatorLog base 10, natural log (ln), log base 2 or any base.
- Exponential Growth CalculatorGrowth or decay by a percent per period.
- Golden Ratio CalculatorSplit a length in the golden ratio.
- Quadratic Formula CalculatorRoots of ax² + bx + c = 0, the discriminant and the vertex.
- Cubic Equation CalculatorAll three roots of a cubic, real or complex.
- Synthetic Division CalculatorDivide a polynomial by x − c.
- Complex Number CalculatorMultiply, divide and convert a + bi numbers.
- Pythagorean Theorem CalculatorHypotenuse or missing side of a right triangle, with the steps.
- Trigonometry Calculatorsin, cos, tan and exact values of any angle.
- Triangle CalculatorEvery side and angle, area and perimeter from three values.
- Circle CalculatorArea, circumference, radius and diameter from any one of them.
- Ellipse CalculatorPerimeter, area, eccentricity and foci.
- Distance Formula CalculatorDistance, midpoint and slope between two points.
- Midpoint CalculatorMidpoint of two points, or the missing endpoint.
- Line Equation CalculatorEquation of a line through two points.
- Degrees Minutes Seconds CalculatorDMS to decimal degrees and back.
- Distance Between Coordinates CalculatorGreat-circle distance from latitude and longitude.
- Scientific Notation CalculatorScientific, E and engineering notation, and back to decimals.
- Percent Error CalculatorPercent error of a measurement.
- Matrix CalculatorDeterminant, inverse, transpose and products.
- Vector CalculatorDot and cross products, magnitude and angle.
- System of Equations CalculatorSolve 2 or 3 linear equations as you write them.
- Sequence CalculatorArithmetic and geometric nth term and sum.
- Surface Area CalculatorSurface area of cylinders, spheres, cones and boxes.
- Right Triangle CalculatorEvery side and angle from any two values.
- Number to Words ConverterNumbers and check amounts written out in words.
- Fraction to Percent CalculatorFractions, decimals and percents, any direction.
- Prime Number CalculatorIs it prime? Nearest primes and primes in a range.
- Arc Length CalculatorArc length, sector area and chord of a circle.
- Polygon CalculatorAngles and area of a regular polygon.
- Polygon Area from CoordinatesShoelace formula area from x, y points.
- Significant Figures CalculatorCount sig figs and round to any number of them.
- Decimal to Fraction CalculatorDecimals to fractions exactly, repeating ones too, and back.
- Long Division CalculatorQuotient and remainder with every step shown.
- Modulo Calculatora mod n — the remainder, for any size.
- Roman Numeral ConverterNumbers to Roman numerals and back, 1 to 3,999.
- Factorial CalculatorExact n! up to 5,000, with digits and zeros.
- Linear Interpolation CalculatorA value between two known points.
- Polar Coordinates CalculatorRectangular to polar and back.
- Pascal’s Triangle CalculatorAny row and entry, exact.
- Parabola CalculatorVertex, focus, directrix and latus rectum.
- Circle Equation CalculatorStandard ↔ general form, center and radius.
- Hyperbola CalculatorCenter, vertices, foci and asymptotes.
- Completing the Square CalculatorVertex form and roots, step by step.
- Fibonacci Calculatorn-th term, sum, list and Fibonacci test.
- Polynomial CalculatorAdd, subtract, multiply and divide polynomials, with steps.
- Derivative CalculatorDerivative of f(x) with the rules shown, plus its value at a point.
- Integral CalculatorDefinite integrals with an error estimate, and antiderivatives.
- Equation SolverSolve an equation in one unknown, with steps and a check.
- Summation CalculatorSigma notation: exact sum, series formulas, partial sums.
- Taylor Series CalculatorTaylor and Maclaurin polynomials with exact coefficients and error.
- Partial Fractions CalculatorDecompose a rational function, with steps and an exact check.
- Collatz Sequence CalculatorThe 3n + 1 sequence: steps to reach 1, peak value, stopping time and the longest chain below a limit.
- Magic Square CalculatorBuild a magic square of any order from 3 to 30 and check your own grid against the magic constant.
- Law of Sines CalculatorSolve AAS, ASA and the ambiguous SSA case: 0, 1 or 2 triangles.
- Linear Programming CalculatorMax or min of a two-variable objective by the corner-point method.
- Binomial Expansion CalculatorExpand (ax + b)^n, find the k-th term or the coefficient of x^m.
- Inequality SolverLinear, quadratic, rational and absolute value inequalities in interval notation.
- Asymptote CalculatorVertical, horizontal and slant asymptotes, holes and intercepts.
- Conic Section CalculatorIdentify the conic in Ax² + Bxy + Cy² + Dx + Ey + F = 0; rotate and find foci.
Everyday life
Tips, discounts, sales tax and grades.
- Tip CalculatorTip, total and each person's share of the bill.
- Discount CalculatorSale price and savings, with stacked discounts and tax.
- Sales Tax CalculatorSales tax and total, or the price before tax from a total.
- GPA CalculatorSemester and cumulative GPA on a 4.0 scale.
- Grade CalculatorWeighted class grade and the final exam score you need.
- Unit Price CalculatorPrice per ounce, pound or item — which package is the better buy.
- PPI CalculatorPixels per inch of any screen.
- Print Size CalculatorPixels and DPI to print size.
- Download Time CalculatorFile size and speed to time.
- TV Size CalculatorBest TV size and seating distance.
- Reading Time CalculatorHow long a text takes to read.
- Ring Size CalculatorUS ring size to diameter and back.
- Lottery Odds CalculatorPowerball, Mega Millions and more.
- Pace CalculatorRunning pace per mile or km, finish time and race times.
- Overtime CalculatorWeekly pay with time and a half over 40 hours.
- Price per Square Foot CalculatorCost per square foot of a home, rent or flooring.
- Heat Index CalculatorFeels-like temperature from heat and humidity.
- Wind Chill CalculatorFeels-like temperature from cold and wind.
- Beaufort Scale CalculatorWind speed to Beaufort force.
- Dew Point CalculatorDew point from humidity, or humidity from dew point.
- Dog Age CalculatorDog years to human years, by the AVMA chart.
- Cat Age CalculatorCat years to human years, by the AVMA chart.
- Age on Other Planets CalculatorYour age in Mars and Jupiter years.
- Golf Handicap CalculatorHandicap Index and Course Handicap from your scores.
- Elo Rating CalculatorExpected score and rating change for chess games.
- Depth of Field CalculatorSharp range and hyperfocal distance for any lens.
- Pet Calorie CalculatorDaily calories for a dog or cat, and cups of food.
- Bike Gear CalculatorGear ratio, gear inches and speed at your cadence.
- Field of View CalculatorAngle of view, crop factor and the scene a lens covers.
- Baseball Stats CalculatorAVG, OBP, SLG, OPS, ERA and WHIP from a stat line.
- Generation CalculatorWhich generation you belong to, with Pew birth years and ages.
- Exposure Value CalculatorEV, equivalent exposures, stops and ND filters.
- Word Count CalculatorWords, characters, sentences and a limit check for X posts and SMS.
- Typing Speed CalculatorWords per minute and accuracy from characters, time and errors.
- Paper Size CalculatorA4, Letter, Legal and more in inches and millimeters.
- Shoe Size CalculatorFoot length to US, UK and EU shoe sizes, men, women and kids.
- Zodiac Sign CalculatorSun sign, Chinese zodiac animal and birthstone from a birth date.
- Christmas Lights CalculatorStrings for a tree or roofline, and the circuit load.
- Time-Lapse CalculatorInterval, frames, clip length and card space.
- Dimensional Weight CalculatorDIM weight and billable weight for UPS, FedEx and USPS.
- Readability CalculatorGrade level and reading ease of a text, six formulas.
- Grade Curve CalculatorCurve test scores five ways, before and after.
- Target GPA CalculatorThe GPA you need in your remaining credits.
- Reading Plan CalculatorPages and minutes a day to finish a book by a date.
- Spaced Repetition CalculatorReview dates for a card: SM-2, Leitner, forgetting curve.
- Study Hours per Credit CalculatorWeekly study time from credit hours, and does it fit in 168.
- Roommate Rent Split CalculatorSplit rent by room size, private bath or income.
- Wedding Budget CalculatorSplit a wedding budget by category and guest.
- Carbon Footprint CalculatorHousehold CO₂e a year from power, gas, car and flights.
- Lightning Distance CalculatorSeconds between flash and thunder to miles or km.
- Tournament Bracket CalculatorGames, rounds, byes and seeding for single or double elimination.
- Round-Robin CalculatorGames, rounds and a full circle-method schedule for any league.
- Bowling Handicap CalculatorUSBC handicap from your average, league base and percentage.
- Darts Checkout CalculatorThe shortest finish for any score up to 170, plus your 3-dart average.
- Aquarium Volume CalculatorGallons of water in a tank after substrate and decor, filled weight, weekly water change and inch per gallon.
- Dog Pregnancy Due Date CalculatorWhelping date from the breeding, ovulation or LH surge date, with ultrasound, X-ray and temperature milestones.
- Cycling Speed and Power CalculatorWatts for a speed, speed for your watts, and hill climb time.
- Swim Pace CalculatorPace per 100 yards or meters, and your critical swim speed.
- Word Game Score CalculatorScore a word with letter values, double and triple squares, blanks and the 50-point seven-tile bonus.
- Flight Distance CalculatorAirport-to-airport miles, bearing and flight time.
- Speaker Wire Gauge CalculatorWire gauge by length and impedance, with power loss and damping factor.
- Internet Speed Needed CalculatorHow many Mbps your home needs for streaming, calls and gaming.
- Projector Throw Distance CalculatorDistance from screen size and throw ratio, or screen size from distance.
- Hiking Time CalculatorHiking time from distance and climb: Naismith, Langmuir and Tobler.
- Backpack Weight CalculatorPack weight from a gear list, food, water and fuel, with base weight.
- Trail Water CalculatorHow much water to carry between sources, and what it weighs.
- Snow Water Equivalent CalculatorWater depth in snow from depth and density, or snow to melt for water.
- Passer Rating CalculatorNFL passer rating (0 to 158.3) or college efficiency from a passing line.
- True Shooting CalculatorTS%, eFG% and points per shot from a shooting line.
- Cricket Run Rate CalculatorRun rate, required run rate and net run rate (NRR).
- Pitch Count CalculatorRest days and next eligible date for youth baseball pitchers.
- Meeting Cost CalculatorWhat a meeting costs per minute and per year.
- Commute Cost CalculatorYearly cost and hours of driving to work.
- Split Expenses CalculatorWho owes whom for shared costs, equal or unequal shares.
Unit conversion
Length, weight, volume, temperature and more.
- Length ConverterInches, feet, miles, centimeters, meters and kilometers.
- Weight ConverterPounds, ounces, stone, tons, grams and kilograms.
- Volume ConverterGallons, quarts, cups, fluid ounces, liters and cubic feet.
- Temperature ConverterFahrenheit, Celsius and Kelvin, with the formulas.
- Area ConverterSquare feet, square meters, acres and hectares.
- Speed Convertermph, km/h, knots, meters and feet per second.
- Pressure Converterpsi, kPa, bar, atmospheres and inches of mercury.
- Energy ConverterkWh, BTU, therms, joules and calories.
- Power ConverterWatts, kilowatts, horsepower and BTU per hour.
- Data Storage ConverterBytes, MB, GB and TB — decimal and binary.
- Angle ConverterDegrees, radians, gradians and turns.
- Time ConverterSeconds, minutes, hours, days, weeks and years.
- Torque ConverterPound-feet, newton-meters and pound-inches.
- Flow Rate ConverterGPM, liters per minute, CFM and m³/h.
- Inches to Centimeters ConverterInches to cm and back, with a chart.
- Centimeters to Inches Convertercm to inches and back, with a chart.
- Feet to Meters ConverterFeet to meters and back, with a chart.
- Meters to Feet ConverterMeters to feet and back, with a chart.
- Pounds to Kilograms ConverterPounds to kg and back, with a chart.
- Kilograms to Pounds Converterkg to lbs and back, with a chart.
- Fahrenheit to Celsius Converter°F to °C and back, with oven temperatures.
- Celsius to Fahrenheit Converter°C to °F and back, with a chart.
- Miles to Kilometers ConverterMiles to km and back, with race distances.
- Kilometers to Miles Converterkm to miles and back, with race distances.
- Ounces to Grams ConverterOunces to grams and back, with a chart.
- Grams to Ounces ConverterGrams to ounces and back, with a chart.
- Millimeters to Inches Convertermm to inches and back, with a chart.
- Inches to Millimeters ConverterInches and fractions to mm, with a chart.
- Feet to Inches ConverterFeet to inches and back, with a chart.
- Inches to Feet ConverterInches to feet and back, with a chart.
- Yards to Feet ConverterYards to feet and back, with a chart.
- Feet to Yards ConverterFeet to yards and back, with a chart.
- Meters to Yards ConverterMeters to yards and back, with a chart.
- Yards to Meters ConverterYards to meters and back, with a chart.
- Centimeters to Feet ConverterCentimeters to feet and back, with a chart.
- Feet to Centimeters ConverterFeet to centimeters and back, with a chart.
- Miles to Feet ConverterMiles to feet and back, with a chart.
- Feet to Miles ConverterFeet to miles and back, with a chart.
- Ounces to Pounds ConverterOunces to pounds and back, with a chart.
- Pounds to Ounces ConverterPounds to ounces and back, with a chart.
- Grams to Pounds ConverterGrams to pounds and back, with a chart.
- Pounds to Grams ConverterPounds to grams and back, with a chart.
- Stone to Pounds ConverterStone to pounds and back, with a chart.
- Pounds to Stone ConverterPounds to stone and back, with a chart.
- Stone to Kilograms ConverterStone to kilograms and back, with a chart.
- Kilograms to Stone ConverterKilograms to stone and back, with a chart.
- Cups to Milliliters ConverterCups to milliliters and back, with a chart.
- Milliliters to Cups ConverterMilliliters to cups and back, with a chart.
- Cups to Ounces ConverterCups to ounces and back, with a chart.
- Ounces to Cups ConverterOunces to cups and back, with a chart.
- Tablespoons to Milliliters ConverterTablespoons to milliliters and back, with a chart.
- Teaspoons to Milliliters ConverterTeaspoons to milliliters and back, with a chart.
- Cups to Tablespoons ConverterCups to tablespoons and back, with a chart.
- Quarts to Cups ConverterQuarts to cups and back, with a chart.
- Gallons to Quarts ConverterGallons to quarts and back, with a chart.
- Cubic Feet to Gallons ConverterCubic feet to gallons and back, with a chart.
- Gallons to Cubic Feet ConverterGallons to cubic feet and back, with a chart.
- Liters to Ounces ConverterLiters to ounces and back, with a chart.
- Celsius to Kelvin ConverterCelsius to kelvin and back, with a chart.
- Kelvin to Celsius ConverterKelvin to celsius and back, with a chart.
- Square Feet to Square Meters ConverterSquare feet to square meters and back, with a chart.
- Square Meters to Square Feet ConverterSquare meters to square feet and back, with a chart.
- Acres to Square Feet ConverterAcres to square feet and back, with a chart.
- Square Feet to Acres ConverterSquare feet to acres and back, with a chart.
- Acres to Hectares ConverterAcres to hectares and back, with a chart.
- Hectares to Acres ConverterHectares to acres and back, with a chart.
- MPH to km/h ConverterMPH to km/h and back, with a chart.
- km/h to MPH Converterkm/h to mph and back, with a chart.
- Knots to MPH ConverterKnots to mph and back, with a chart.
- MPH to Knots ConverterMPH to knots and back, with a chart.
- PSI to Bar ConverterPSI to bar and back, with a chart.
- Bar to PSI ConverterBar to psi and back, with a chart.
- kPa to PSI ConverterkPa to psi and back, with a chart.
- PSI to kPa ConverterPSI to kpa and back, with a chart.
- kJ to kcal ConverterKilojoules to calories (kcal) and back, with a chart.
- kcal to kJ ConverterCalories (kcal) to kilojoules and back, with a chart.
- HP to kW ConverterHorsepower to kilowatts and back, with a chart.
- kW to HP ConverterKilowatts to horsepower and back, with a chart.
- Milliliters to Ounces ConvertermL to fluid ounces and back, with a chart.
- Ounces to Milliliters ConverterFluid ounces to mL and back, with a chart.
- Liters to Gallons ConverterLiters to US gallons and back, with a chart.
- Gallons to Liters ConverterUS gallons to liters and back, with a chart.
- Degrees to Radians ConverterDegrees to radians and back, with common angles.
- Radians to Degrees ConverterRadians to degrees and back, with a chart.
- Color ConverterHEX, RGB and HSL color codes, with contrast.
Food & cooking
Kitchen measures, recipes, baking and cooking times.
- Cooking Measurement ConverterCups, tablespoons, teaspoons, sticks of butter and milliliters.
- Cups to Grams ConverterFlour, sugar, butter and more — cups to grams and back.
- Recipe ScalerDouble, halve or resize a recipe for any number of servings.
- Cake Pan ConverterHow much batter for a different pan size or shape.
- Pizza Size CalculatorCompare pizzas by area and price per square inch.
- Baker's Percentage CalculatorBaker's percentages and dough hydration, or weights from a formula.
- Yeast ConverterActive dry, instant and fresh yeast.
- Turkey CalculatorTurkey size, thawing and roasting time, by USDA.
- Ham Cooking Time CalculatorBaking time and temperature by USDA.
- Chicken Cooking Time CalculatorUSDA roasting, simmering and grilling times.
- Meat Temperature ChartSafe internal temperatures for meat, poultry, fish and eggs.
- Canning Altitude CalculatorPressure canner PSI for your elevation.
- Oven Temperature ConverterFahrenheit, Celsius and gas mark for recipes.
- Coffee Ratio CalculatorCoffee to water ratio, checked against the SCA Golden Cup.
- Butter ConverterSticks of butter to cups, tablespoons, ounces and grams.
- High Altitude Baking CalculatorAdjust baking powder, sugar, liquid and oven for elevation.
- Brine CalculatorSalt for a brine by weight, in kosher or table salt.
- Prime Rib Cooking Time CalculatorRoasting time by weight and pull temperature.
- ABV CalculatorAlcohol by volume from original and final gravity.
- Pork Cooking Time CalculatorUSDA times for roasts, chops and tenderloin.
- Lamb Cooking Time CalculatorUSDA times for leg, shoulder, chops and shanks.
- Food Shelf Life CalculatorHow long food keeps in the pantry, fridge or freezer, from USDA FoodKeeper.
- Candy Temperature CalculatorCandy stages in °F and °C, adjusted for your elevation.
- Keg CalculatorServings per keg, kegs for a party and CO2 pressure.
- Party Food CalculatorAppetizers, meat and drinks per guest for a party.
- Recipe ResizerResize a recipe by servings or pan size, with grams.
- Food Cost CalculatorRecipe cost per portion with trim loss, menu price from a target food cost %, margin and prime cost.
- Maple Syrup CalculatorSap to syrup by the Rule of 86, syrup per tap and the finishing temperature.
- Coffee Extraction CalculatorExtraction yield from dose, brew weight and TDS, against the Golden Cup range.
- Sourdough Feeding CalculatorStarter, flour and water for 1:1:1, 1:5:5 or any ratio, and the levain for a recipe.
- Ferment Salt CalculatorSalt for sauerkraut by cabbage weight and for pickle brine by water weight.
- Camp Food CalculatorHow much food to pack per person per day, with calories and density.
- Strike Water Temp CalculatorMash strike water temperature, hot water to raise a mash, multi-rest schedule.
- Priming Sugar CalculatorSugar for bottle conditioning homebrew, by batch size, temperature and CO2 volumes.
- IBU CalculatorBeer bitterness from hop additions by the Tinseth formula, Rager for comparison.
- Beer Color Calculator (SRM)Beer color in SRM and EBC from the grain bill, by the Morey equation.
- Pizza Dough CalculatorFlour, water, salt and yeast for any number of pizzas, by baker's percentage.
- Yeast Pitch Rate CalculatorCells to pitch for beer, in liquid packs or dry yeast, by volume and gravity.
Auto & travel
Gas mileage, trip cost, tires, engines and drive time.
- Gas Mileage CalculatorMPG, liters per 100 km and fuel cost per mile.
- Driving CO₂ CalculatorCar CO₂ emissions from miles and mpg.
- Fuel Cost CalculatorGas cost of a trip, round trip and per person.
- Mileage Reimbursement Calculator2026 IRS mileage rates.
- Tire Size CalculatorTire diameter and sidewall, and how a new size changes the speedometer.
- RPM to MPH CalculatorSpeed from RPM, gears and tire size.
- Horsepower CalculatorHorsepower from torque and RPM, or torque from horsepower.
- Engine Displacement CalculatorCubic inches, cc and liters from bore, stroke and cylinders.
- Compression Ratio CalculatorStatic compression ratio of an engine.
- Travel Time CalculatorDrive time and arrival time from distance, speed and stops.
- Stopping Distance CalculatorReaction and braking distance from your speed.
- Tongue Weight CalculatorRecommended trailer tongue weight.
- EV Charging CalculatorElectric car charging time and cost.
- MPGe CalculatorkWh/100 mi to MPGe and cost.
- Quarter Mile Calculator1/4-mile ET and trap speed from weight and horsepower.
- Wheel Offset CalculatorCompare wheel offset: poke, clearance and backspacing.
- EV vs Gas Cost CalculatorFuel cost per mile, per year and payback.
- Density Altitude CalculatorPressure and density altitude, plus crosswind.
- Tire Load Index CalculatorDecode a tire sidewall: load index, speed rating and size.
- Crosswind Component CalculatorCrosswind and headwind from runway, wind and gusts.
- Car Affordability CalculatorCar price you can afford under the 20/4/10 guideline.
- EV Range in Cold Weather CalculatorWinter range of an electric car, with and without the heater.
- Road Trip Cost CalculatorWhole-trip cost: gas, hotels, food and tolls, per person.
- Oil Change Cost CalculatorSynthetic vs conventional per year, shop or DIY.
- Injector Size CalculatorFuel injector flow in lb/hr and cc/min for your horsepower.
- Axle Ratio Change CalculatorEngine RPM before and after a new axle ratio or tire size.
- Speedometer Error CalculatorReal speed and odometer error after new tires or gears, or against GPS.
- Boost and Airflow CalculatorTurbo pressure ratio, airflow in lb/min and charge air temperature.
- Tire Tread Life CalculatorMiles and months left on your tires from tread depth and wear.
- Car Battery CCA CalculatorCold cranking amps your engine needs and battery charge from voltage.
Finance
Mortgages, loans, interest, savings and pay.
- Mortgage CalculatorMonthly payment with taxes, insurance, PMI and extra payments.
- Loan CalculatorMonthly payment and total interest on any loan.
- Auto Loan CalculatorCar payment with down payment, trade-in and sales tax.
- Car Lease CalculatorMonthly lease payment from money factor and residual.
- Compound Interest CalculatorSavings growth with monthly contributions, year by year.
- Simple Interest CalculatorInterest and total from principal, rate and time.
- Savings Goal CalculatorHow much to save each month to reach a goal.
- 401(k) CalculatorYour 401(k) at retirement with employer match.
- Social Security CalculatorFull retirement age and benefit by claiming age.
- RMD CalculatorRequired minimum distribution from the IRS table.
- Roth IRA Calculator2026 Roth limit by income, and growth.
- Credit Card Payoff CalculatorMonths to pay off a card and the interest you pay.
- Credit Card Interest CalculatorInterest for a billing cycle from the APR.
- Salary CalculatorHourly to salary and back, per week, month and year.
- Income Tax Calculator 2026Federal income tax with the 2026 brackets.
- Paycheck Calculator 2026Take-home pay after federal tax and FICA.
- Bonus Tax Calculator2026 withholding on a bonus.
- Self-Employment Tax Calculator2026 SE tax from your net profit.
- Capital Gains Tax Calculator2026 tax on a stock or property gain.
- Raise CalculatorNew salary from a raise, or the raise percentage.
- ROI CalculatorReturn on investment and the annualized return.
- Cap Rate CalculatorCapitalization rate and NOI.
- CAGR CalculatorCompound annual growth rate.
- Stock Average CalculatorAverage cost per share across purchases.
- Dividend CalculatorDividend yield and income.
- Margin CalculatorProfit margin and markup, or the price for a margin.
- Price Elasticity CalculatorElasticity of demand, midpoint method.
- Break-Even CalculatorUnits and sales you need to cover your costs.
- EOQ CalculatorEconomic order quantity.
- Depreciation CalculatorStraight-line, declining balance and MACRS.
- Inflation CalculatorWhat dollars from any year since 1913 are worth today.
- Real Return CalculatorReturn after inflation, by the Fisher equation.
- APY CalculatorAPR to APY and back, for any compounding.
- CD CalculatorCD interest and value at maturity.
- Bond Yield CalculatorYield to maturity and current yield.
- Tax-Equivalent Yield CalculatorMunicipal bond yield vs. taxable.
- Future Value CalculatorWhat money and payments grow to.
- Present Value CalculatorWhat future money is worth today.
- Annuity Payout CalculatorRegular payout from a lump sum.
- Retirement Withdrawal CalculatorHow long your savings will last.
- NPV CalculatorNet present value, IRR and payback period.
- Amortization CalculatorMonth-by-month loan schedule: interest, principal, balance.
- Loan Payoff CalculatorPayoff date and interest saved by paying extra.
- Refinance CalculatorMonthly savings and break-even on a refinance.
- HELOC CalculatorHELOC draw and repayment payments.
- Biweekly Mortgage CalculatorInterest and time saved paying every two weeks.
- Mortgage Recast CalculatorNew payment after a lump sum.
- Balloon Payment CalculatorMonthly payment and the balloon due at the end.
- Interest-Only Mortgage CalculatorPayment during and after interest-only.
- Mortgage Points CalculatorBreak-even on buying discount points.
- APR CalculatorAnnual percentage rate including fees.
- Commission CalculatorSales commission and total pay with a base salary.
- Rule of 72 CalculatorHow long money takes to double at a rate.
- Down Payment CalculatorDown payment, loan amount and time to save.
- Loan-to-Value CalculatorLTV, CLTV and when PMI can end.
- Home Affordability CalculatorHow much house fits your income.
- Debt-to-Income Ratio CalculatorYour DTI for mortgages and loans.
- Rent Affordability CalculatorHow much rent fits 30% of your income.
- Net Worth CalculatorWhat you own minus what you owe.
- 50/30/20 Budget CalculatorNeeds, wants and savings from take-home pay.
- Debt Payoff CalculatorSnowball vs avalanche: months to debt-free and interest.
- WACC CalculatorWeighted average cost of capital, with CAPM.
- Interest Rate CalculatorFind the rate on a loan from its payment and term.
- HSA Contribution Calculator2026 HSA limit, catch-up and partial-year coverage.
- Loan Comparison CalculatorCompare 2–3 offers: payment, interest, points and fees.
- Student Loan CalculatorPayment, interest and payoff date; Standard, Extended, Tiered.
- Traditional IRA Calculator2026 IRA deduction by income and workplace plan.
- FHA Loan CalculatorPayment with upfront and annual MIP, and when MIP ends.
- VA Loan CalculatorPayment with the VA funding fee, no monthly mortgage insurance.
- Rental Property CalculatorCash flow, cap rate, cash-on-cash return and DSCR.
- Retirement CalculatorSavings at retirement, what you need and how much more to save.
- Rent vs Buy CalculatorNet worth of buying vs renting, year by year, and the break-even year.
- USDA Loan CalculatorPayment with the USDA upfront and annual guarantee fees.
- PMI CalculatorMonthly PMI, when to cancel it at 80% and when it ends at 78%.
- Quarterly Estimated Tax Calculator2026 estimated tax payments, due dates and safe harbors.
- Home Sale Exclusion CalculatorSection 121 exclusion, taxable gain and tax on selling your home.
- Black-Scholes CalculatorEuropean option price, Greeks and implied volatility.
- Child Tax Credit Calculator2026 child tax credit, other dependents and the refundable part.
- Sharpe Ratio CalculatorSharpe and Sortino ratios from returns or from return and volatility.
- College Savings CalculatorMonthly saving for college with cost growth, 529 rules and a year-by-year table.
- Dollar-Cost Averaging CalculatorFixed-amount investing: average cost, gain and lump sum comparison.
- Kelly Criterion CalculatorOptimal bet size from win probability and odds, growth per bet, half Kelly and the investing form.
- VAT CalculatorAdd VAT, remove VAT or find the rate: several lines, rounding choice, dated UK, EU, Canada, Australia and NZ rates.
- Closing Cost CalculatorBuyer closing costs and cash to close by Loan Estimate sections A–J, with prepaids and the RESPA escrow cushion.
- FIRE CalculatorFI number at 4%, 3.5% and 3%, years to financial independence, Coast FI and years by savings rate.
- Freelance Rate CalculatorHourly and day rate for your income goal after self-employment tax, insurance, expenses and unpaid time.
- Prorated Rent CalculatorRent for a partial month by actual days, 30-day month or 365 days, with move-in total and deposit checks.
- Financial Ratios CalculatorCurrent and quick ratio, debt-to-equity, margins, ROA, ROE, turnover and DSO from statement figures.
- Home Sale Net Proceeds CalculatorSeller's net sheet: sale price minus payoff, commissions, closing costs, transfer tax, repairs and prorated property tax.
- Emergency Fund CalculatorMonths of expenses to save, the gap and the time to reach it.
- Short-Term Rental CalculatorAirbnb profit, break-even occupancy, and long-term comparison.
- Social Security Break-Even CalculatorTotal benefits at 62, full age or 70, and the break-even age.
- Payback Period CalculatorSimple and discounted payback, profitability index and NPV.
- IRR CalculatorIRR, MIRR and XIRR for dated cash flows, with a warning for several IRRs.
- LTV to CAC CalculatorCustomer lifetime value, CAC payback in months and the LTV:CAC ratio.
- PTO Accrual CalculatorPaid time off per pay period or per hours worked, balance, cap and carryover.
- Price Increase CalculatorHow many sales you can lose after a price rise, or the price that covers a cost increase.
- Invoice Late Fee CalculatorDue date, days overdue, late fee and aging buckets for unpaid invoices.
- Property Tax CalculatorYearly property tax and monthly escrow from mills, assessment ratio and exemptions.
- Federal Estate Tax Calculator2026 federal estate tax: $15 million exclusion, 40% top rate, portability.
- Gift Tax Calculator2026 gift tax: $19,000 annual exclusion, Form 709, lifetime exemption.
- Federal Poverty Level Calculator2026 poverty guideline by household size and your income as a percent of FPL.
- Standard vs Itemized Deduction CalculatorWhich is bigger in 2026: the standard deduction or itemizing (SALT cap, mortgage, charity, medical).
- Employer Payroll Tax CalculatorWhat an employee really costs in 2026: employer FICA, FUTA, state unemployment, workers comp.
- Trade-In Equity CalculatorPositive or negative equity, and the cost of rolling it into a new loan.
- Flip 70% Rule CalculatorMax offer from ARV and repairs, then real flip profit.
- DSCR CalculatorDebt service coverage and the largest loan your NOI supports.
- Gross Rent Multiplier CalculatorGRM, value from rent, and the 1% rule ratio.
- Rent Increase CalculatorNew rent, percent increase, rent cap check and notice.
- Rental Vacancy Rate CalculatorRent lost to vacancy and break-even occupancy.
- Rental Property Depreciation Calculator27.5-year deduction and the tax on recapture at sale.
- Net Price CalculatorCollege cost after grants per year and for four years, plus the gap.
- Student Loan Repayment Plans CalculatorStandard, Extended, Graduated, Tiered Standard and RAP side by side.
- PSLF CalculatorPublic Service Loan Forgiveness: payments left, date and forgiven balance.
- Scholarship Tax CalculatorTaxable part of a scholarship and its effect on AOTC and lifetime learning credit.
- Student Aid Index (SAI) CalculatorEstimate the SAI and Pell Grant for a dependent student (2027–28 formula).
- Work-Study Earnings CalculatorHours times wage against your award, weekly hours cap, FICA and SAI effect.
- Credit Utilization CalculatorCredit utilization overall and per card, and the payment that reaches your target.
- Pension Lump Sum vs Annuity CalculatorLump sum or monthly pension: break-even return, present value and payback time.
- Roth Conversion Tax Calculator 2026Federal tax on converting a traditional IRA to Roth, bracket by bracket.
- IRA Pro-Rata Rule CalculatorTaxable part of a backdoor Roth conversion by the pro-rata rule on Form 8606.
- Forex Pip Value CalculatorPip value in your account currency, position size from risk and margin.
- Option Payoff CalculatorBreak-even, max profit and loss of calls, puts and spreads at expiration.
- Social Security Tax CalculatorHow much of your Social Security is taxable: 0, 50 or 85%.
- Medicare IRMAA CalculatorYour 2026 Part B premium and Part D surcharge by income.
- Social Security Earnings Test CalculatorBenefits withheld if you claim early and keep working.
- Spousal Benefit CalculatorSocial Security spousal and survivor benefit estimates.
- Medicare Late Enrollment Penalty CalculatorPart B, Part D and Part A penalty for signing up late.
- SSI Income CalculatorCountable income and the federal SSI payment for 2026.
- Subscription Cost CalculatorMonthly and yearly total of your subscriptions.
- Latte Factor CalculatorWhat a small daily spend could grow to if invested.
Health & fitness
BMI, calories, heart rate, body fat and pregnancy dates.
- BMI CalculatorBody mass index and the CDC category for adults.
- Calorie CalculatorDaily calorie needs by age and activity, and resting calories.
- BMR CalculatorCalories you burn at rest, two standard equations.
- Protein CalculatorDaily protein allowance from your weight.
- Fiber Intake CalculatorDaily fiber by age and sex.
- Macro CalculatorGrams of carbs, protein and fat for your calories.
- Water Intake CalculatorHow much water a day, by the National Academies.
- Standard Drink CalculatorUS standard drinks in any beer, wine or spirit.
- Calories Burned CalculatorCalories burned walking, running, cycling and more.
- One Rep Max CalculatorEstimate your 1RM from any set of reps.
- Ideal Weight CalculatorDevine formula weight and the healthy BMI range.
- Body Fat CalculatorBody fat percentage by the Navy tape measure method.
- Lean Body Mass CalculatorLean mass by the Boer, James and Hume formulas.
- Waist-to-Hip Ratio CalculatorYour WHR and the WHO risk cutoffs.
- Waist-to-Height Ratio CalculatorYour WHtR and the NICE categories.
- Body Surface Area CalculatorBSA by the Mosteller, Du Bois and Haycock formulas.
- Total Body Water CalculatorBody water by the Watson formula.
- Blood Volume CalculatorNadler blood volume estimate.
- Army Body Fat CalculatorThe 2026 Army waist-to-height standard.
- Target Heart Rate CalculatorMaximum heart rate and exercise zones by age.
- Heart Rate Reserve CalculatorKarvonen target heart rate zones.
- VO2 Max CalculatorVO2 max from the Cooper 12-minute run.
- Race Time Predictor5K to marathon times from one race.
- Pack-Year CalculatorPack-years and lung screening criteria.
- Due Date CalculatorPregnancy due date and how far along you are.
- Pregnancy Week CalculatorHow many weeks pregnant you are, on any date.
- Conception CalculatorEstimated conception date and fertile window.
- Adjusted Age CalculatorCorrected age for premature babies.
- Ovulation CalculatorFertile window and ovulation date for the next cycles.
- Period CalculatorWhen your next periods are due.
- Pregnancy Weight Gain CalculatorRecommended gain by pre-pregnancy BMI, IOM guidelines.
- A1C CalculatorA1C to average blood sugar and back.
- Corrected Calcium CalculatorCalcium adjusted for albumin.
- Serum Osmolality CalculatorCalculated osmolality and gap.
- Anion Gap CalculatorAnion gap with albumin correction.
- Corrected Sodium CalculatorSodium corrected for high glucose.
- eGFR CalculatorKidney function by the CKD-EPI 2021 equation.
- Creatinine Clearance CalculatorCockcroft-Gault estimate in mL/min.
- Blood Pressure CalculatorYour reading on the AHA category chart.
- LDL Cholesterol CalculatorFriedewald LDL from a lipid panel.
- Mean Arterial Pressure CalculatorMAP from systolic and diastolic.
- QTc CalculatorCorrected QT by four formulas.
- IV Drip Rate CalculatorDrops per minute and mL per hour.
- Maintenance Fluid CalculatorHolliday-Segar and 4-2-1 rule.
- Sleep CalculatorBedtime or wake-up time by sleep cycles.
- BMI Calculator for Children and TeensBMI-for-age percentile and CDC category, ages 2–19.
- Baby Growth Percentile CalculatorWeight, length and head percentiles on the CDC charts.
- Child Height Predictor CalculatorAdult height from the parents’ heights, with range.
- BAC CalculatorRough blood alcohol range from drinks, weight and time.
- HOMA-IR CalculatorInsulin resistance index from fasting glucose and insulin.
- Caffeine in Body CalculatorCaffeine left at bedtime and when it drops to your level.
- VDOT CalculatorVDOT from a race, equivalent times and training paces.
- Steps to Miles CalculatorSteps to miles, time and calories, or steps for a distance.
- Glasgow Coma Scale CalculatorGCS total from eye, verbal and motor scores (educational).
- Apgar Score CalculatorNewborn Apgar score from the five signs, out of 10.
- Powerlifting DOTS CalculatorDOTS score from bodyweight and total, or the total for a target.
- Baby Formula Amount CalculatorOunces of formula per day and per feeding by weight (AAP).
- Herd Immunity CalculatorThreshold from R0, vaccine coverage needed, and a simple SIR model.
- PHQ-9 CalculatorPHQ-9 depression screening score, 0 to 27.
- GAD-7 CalculatorGAD-7 anxiety screening score, 0 to 21.
- CURB-65 CalculatorPneumonia severity score from five bedside findings.
- CHA2DS2-VASc CalculatorStroke risk score in atrial fibrillation, 0 to 9.
- Centor Score CalculatorModified Centor (McIsaac) score for a sore throat.
- Parkland Formula CalculatorBurn fluid estimate: 4 mL x kg x % burned over 24 hours.
- Sunscreen CalculatorHow much sunscreen to use, how often, what SPF blocks.
- Breast Milk Storage CalculatorUse-by time for expressed milk: counter, fridge, freezer (CDC).
- Contraction TimerTime contractions and check the 5-1-1 rule.
- Sleep Needs by Age CalculatorHours of sleep for babies, kids, teens and adults, with bedtime.
- Pregnancy Calories CalculatorExtra calories by trimester, BMI and while breastfeeding.
- Kick Count CalculatorLog time to 10 baby movements; the 10-in-2-hours check.
- Diaper Count CalculatorNewborn wet and dirty diapers by day against the AAP guide.
- Cycling Power Zones CalculatorYour FTP, or a 20-minute test, as seven Coggan zones in watts.
- Sweat Rate CalculatorYour sweat loss per hour from weight before and after exercise.
- Rucking Calories CalculatorCalories burned walking with a loaded pack, by Pandolf and Army LCDA.
- Body Roundness Index CalculatorYour BRI from waist and height, with the 2024 NHANES groups.
- FIB-4 CalculatorLiver fibrosis index from age, AST, ALT and platelets (educational).
- MELD Score CalculatorMELD, MELD-Na and MELD 3.0 from six lab values (educational).
- Child-Pugh Score CalculatorCirrhosis class A, B or C from five findings (educational).
- Wells Score CalculatorWells criteria for DVT and pulmonary embolism (educational).
- NEWS2 CalculatorNational Early Warning Score 2 from seven bedside observations (educational).
- Free Water Deficit CalculatorWater deficit in hypernatremia and the Adrogue-Madias 1-liter sodium change (educational).
- Noise Dose CalculatorOSHA and NIOSH noise dose and 8-hour TWA for a shift of several dBA levels.
- WBGT Heat Stress CalculatorWet bulb globe temperature checked against the NIOSH heat alert and exposure limits.
- NIOSH Lifting Equation CalculatorRecommended weight limit and lifting index for a manual lift, in lb or kg.
- Glycemic Load CalculatorGlycemic load per serving and per day from GI and carbs.
- Vitamin IU ConverterIU to mcg or mg for vitamins A, D, E and folate DFE.
- Alcohol Calories CalculatorCalories in beer, wine, spirits or a cocktail from volume and ABV.
- Weight Change Timeline CalculatorWeeks to a goal weight: the 3,500-calorie rule vs an adaptive model.
- Added Sugar CalculatorAdded sugar in grams, teaspoons and calories against AHA limits.
- Sodium Intake CalculatorSodium in your meals vs the 2,300 mg limit; sodium to salt.
- Visual Acuity ConverterSnellen, decimal, logMAR and ETDRS letters.
- Spherical Equivalent CalculatorSphere plus half cylinder; plus and minus cylinder.
- Vertex Distance CalculatorGlasses power to contact lens power.
- Reading Add CalculatorEstimated near add by age and distance.
- Lens Thickness CalculatorEdge and center thickness by index.
- Rowing Pace to Watts CalculatorConcept2 split per 500 m to watts and back, 2000 m time, calories per hour.
- Race Splits CalculatorEven, negative and positive split tables per mile or km for a goal time.
Statistics
Standard deviation, z-scores, probability and samples.
- Standard Deviation CalculatorSample and population standard deviation, with steps.
- Coefficient of Variation CalculatorRelative standard deviation in percent.
- Z-Score CalculatorZ-score, percentile and normal curve probabilities.
- Normal Distribution CalculatorProbabilities and percentiles of a bell curve.
- Probability CalculatorTwo events — both, either, neither — and at least once.
- Bayes’ Theorem CalculatorPositive predictive value of a test.
- Permutation and Combination CalculatornPr and nCr, with or without repetition.
- Confidence Interval CalculatorConfidence interval for a mean with t or z.
- Margin of Error CalculatorMargin of error for a poll or survey.
- Sample Size CalculatorHow many survey responses you need.
- Percentile CalculatorAny percentile, quartiles and percentile rank.
- Quartile CalculatorQ1, Q3, IQR, five-number summary and outliers.
- Linear Regression CalculatorLine of best fit, slope, intercept and R².
- Correlation Coefficient CalculatorPearson's r, R² and its p-value.
- Spearman Correlation CalculatorRank correlation with ties.
- P-Value CalculatorP-value from a z-score or t-statistic.
- Chi-Square CalculatorGoodness-of-fit test and chi-square p-value.
- Chi-Square Test of IndependenceContingency table chi-square test.
- T-Test CalculatorTwo-sample Welch or Student t-test.
- Paired T-Test CalculatorBefore-and-after matched samples.
- One-Way ANOVA CalculatorF statistic and p-value for groups.
- Two-Proportion Z-Test CalculatorCompare two percentages.
- Effect Size CalculatorCohen’s d and Hedges’ g.
- Odds CalculatorAmerican, decimal and fractional odds to probability.
- Relative Risk & Odds Ratio CalculatorRR and OR with 95% confidence intervals.
- Binomial Probability CalculatorExactly, at least and at most k successes.
- Hypergeometric Distribution CalculatorProbabilities without replacement.
- Poisson Distribution CalculatorProbabilities of event counts.
- Expected Value CalculatorProbability-weighted average of outcomes.
- Covariance CalculatorSample and population covariance.
- Mean Absolute Deviation CalculatorMAD about the mean or median.
- Critical Value Calculatorz, t, chi-square and F cutoffs.
- Fisher’s Exact Test Calculator2×2 table exact p-value.
- Standard Error CalculatorSE of a mean, a proportion or a difference.
- Geometric Distribution CalculatorChance of the first success on trial k.
- Exponential Distribution CalculatorWaiting-time probabilities and percentiles.
- F-Test for Two Variances CalculatorCompare two variances: F, p-value, decision.
- Skewness & Kurtosis CalculatorSample and population skewness and excess kurtosis.
- Dice Probability CalculatorExact odds for the sum of n dice, plus 4d6 drop lowest.
- Statistical Power CalculatorPower and sample size for t-tests and two proportions.
- Sensitivity and Specificity CalculatorTest accuracy from a 2×2 table, with 95% intervals.
- Mann–Whitney U Test CalculatorWilcoxon rank-sum test for two independent samples.
- Empirical Rule Calculator68–95–99.7 rule for any mean and SD, plus Chebyshev.
- Birthday Paradox CalculatorChance two people share a birthday, and hash collisions.
- One-Sample T-Test CalculatorTest a mean against a value: t, p, CI, z-test option.
- Wilcoxon Signed-Rank Test CalculatorNonparametric test for paired samples or one median.
- Moving Average CalculatorSimple, weighted and exponential averages of a series.
- Negative Binomial Distribution CalculatorFailures or trials until the r-th success.
- Cohen’s Kappa CalculatorInter-rater agreement with CI and weighted kappa.
- Kruskal-Wallis Test CalculatorCompare 2-8 groups by ranks: H, p-value, Dunn's test.
- One-Proportion Z-Test CalculatorTest a percentage against a value: z, p, exact test, CIs.
- Poker Odds CalculatorPot odds, outs, EV of a call and starting-hand combos.
- Streak Probability CalculatorExact odds of a run in a row, the longest streak and HH vs HT.
- Dice Expression CalculatorOdds for 2d6+3, advantage and attack damage against AC.
- Standard Score Converterz, T, IQ-style, NCE, stanine, sten and percentile.
- Cronbach’s Alpha CalculatorScale reliability, alpha if item deleted, Spearman–Brown.
- Net Promoter Score CalculatorNPS from promoters and detractors, with confidence interval.
- A/B Test Sample Size CalculatorVisitors per variant for a conversion-rate test.
- Likert Scale CalculatorMean, median, top-2-box and percent agree.
- Survey Response Rate CalculatorAAPOR response rates RR1 to RR6 and more.
- Hardy-Weinberg CalculatorAllele and genotype frequencies, carriers and a chi-square equilibrium test.
- Punnett Square CalculatorMonohybrid, dihybrid and multi-gene crosses with ratios and probabilities.
Physics
Force, acceleration, energy, density and motion.
- Force CalculatorForce, mass or acceleration with F = ma.
- Friction CalculatorStatic and kinetic friction force.
- Centripetal Force CalculatorForce and acceleration in circular motion.
- Acceleration CalculatorAcceleration from a change in speed over time.
- Kinetic Energy CalculatorKinetic energy from mass and speed.
- Density CalculatorDensity, mass or volume from the other two.
- Buoyancy CalculatorBuoyant force by Archimedes’ principle.
- Free Fall CalculatorFall time and impact speed from a height.
- Terminal Velocity CalculatorFalling speed with air drag.
- Projectile Motion CalculatorRange, height and flight time of a launch.
- Kinematics CalculatorSolve s, u, v, a, t for constant acceleration.
- Specific Heat CalculatorHeat to warm or cool: Q = mcΔT.
- Speed of Sound CalculatorSpeed of sound in air by temperature.
- Decibel CalculatorAdd dB, distance loss and safe noise time.
- Speed CalculatorSpeed, distance or time from the other two.
- Potential Energy CalculatorGravitational potential energy, mgh.
- Hooke’s Law CalculatorSpring force, spring constant and energy.
- Momentum CalculatorMomentum from mass and velocity.
- Collision CalculatorElastic and inelastic collisions.
- Pressure CalculatorPressure from force and area.
- Wavelength CalculatorWavelength, frequency and photon energy.
- Doppler Effect CalculatorFrequency heard from a moving source.
- Snell’s Law CalculatorRefraction angle and critical angle.
- Thin Lens CalculatorFocal length, image distance and magnification.
- Time Dilation CalculatorLorentz factor and relativistic time.
- Work and Power CalculatorWork from force and distance, and power.
- Torque CalculatorTorque from force, lever arm and angle.
- Half-Life CalculatorAmount remaining after decay, or the half-life.
- Gravitational Force CalculatorNewton's law of gravitation between two masses.
- Coulomb’s Law CalculatorForce between two electric charges.
- Magnetic Field of a Wire CalculatorField around a straight wire.
- Weight on Other Planets CalculatorYour weight on the Moon, Mars and beyond.
- Escape Velocity CalculatorEscape speed for planets and moons.
- Orbital Period CalculatorSatellite orbit speed and period.
- Pendulum CalculatorPeriod and length of a simple pendulum.
- E = mc² CalculatorMass to energy in joules, kWh, MeV and TNT.
- Moment of Inertia CalculatorRod, disk, sphere, hoop or plate, with parallel axis.
- Angular Velocity CalculatorRPM to rad/s, rim speed and centripetal acceleration.
- Reynolds Number CalculatorLaminar or turbulent pipe flow, water and air presets.
- Rocket Equation Calculator (Tsiolkovsky)Delta-v from Isp and mass ratio, or propellant.
- Thermal Expansion CalculatorHow much steel, concrete or a liquid grows with heat.
- Stress, Strain and Young's Modulus CalculatorStress, strain, stretch under load, or the modulus.
- De Broglie Wavelength Calculatorλ = h/p for an electron, proton or any object.
- Blackbody Radiation CalculatorRadiated power, peak wavelength and temperature (Stefan–Boltzmann, Wien).
- Bernoulli Equation CalculatorPressure, speed or height between two points of a flow, plus Torricelli.
- Heat Conduction CalculatorHeat flow through a wall or slab, layered walls and R-values.
- Latent Heat CalculatorHeat to melt, freeze, boil or condense, and the whole ice-to-steam curve.
- Photoelectric Effect CalculatorPhoton energy, electron energy, stopping potential and cut-off for light on a metal.
- Mirror Equation CalculatorConcave and convex mirrors: focal length, image distance and magnification.
- Inclined Plane CalculatorA block on a ramp: acceleration, friction, angle of repose and the force to push it up.
- Newton’s Law of Cooling CalculatorTemperature after a time, time to reach a temperature, and the cooling constant k.
- Carnot Efficiency CalculatorBest efficiency of a heat engine between two temperatures, and the Carnot COP of a refrigerator or heat pump.
- Standing Wave CalculatorHarmonics of a string or an open or closed pipe: frequency, length, wave speed and tension.
- Entropy Change CalculatorEntropy change of heating, melting, gases and mixing, with the second-law check.
- Adiabatic Process CalculatorFinal pressure, volume, temperature, work and heat of an ideal gas in adiabatic, isothermal, isobaric and isochoric processes.
- Angular Momentum CalculatorL = Iω, a particle, conservation when the moment of inertia changes, and torque over time.
- Electric Field CalculatorField and potential of point charges, force on a test charge, and the field between plates.
- Machining Speeds and Feeds CalculatorSpindle RPM, feed rate and removal rate from SFM.
- Radiation Dose CalculatorAdd X-rays, CT scans, flights and background; compare the total.
- Earthquake Energy CalculatorMagnitude to joules, TNT and kWh; compare two quakes.
- Wind Turbine Power CalculatorWatts and yearly kWh from rotor size and wind speed.
- Sheet Metal Bend Allowance CalculatorBend allowance, bend deduction, setback and flat length from K-factor.
- Tap Drill Size CalculatorTap drill for UNC, UNF and metric threads, with percent of thread.
- Beam Deflection CalculatorReactions, moment, stress and deflection of a simple beam or cantilever.
- Bolt Torque CalculatorTightening torque from T = K x D x F for SAE and metric bolts.
- Bolt Circle & Hole Pattern CalculatorX and Y of every hole on a bolt circle or in a row.
- Schwarzschild Radius CalculatorEvent horizon size from any mass, plus photon sphere and clock slowing.
- Drake Equation CalculatorAlien civilizations in the Milky Way, from single values or ranges.
- Redshift and Hubble’s Law CalculatorRedshift z, recession speed and distance with an editable H0.
- Gear Ratio CalculatorGear train ratio, output rpm and torque with losses.
- Pulley System CalculatorMechanical advantage, pull force and rope length with friction.
- Star Magnitude CalculatorBrightness ratios, distance modulus, luminosity and telescope limit.
- Sling Angle CalculatorTension in each sling leg by angle from horizontal, capacity at an angle and the 30 degree minimum.
- Sound Distance CalculatorNoise level at a distance from several sources, or the distance needed to reach a target level.
- Altitude Pressure and Boiling Point CalculatorAir pressure, oxygen and the boiling point of water at any elevation.
- Prism Diopter CalculatorPrism, degrees, shift and Prentice’s rule.
Chemistry
Molarity, dilution, gas law and pH.
- Molarity CalculatorMolarity of a solution, or grams to weigh out.
- Percent to Molarity CalculatorMass percent and density to M.
- Molality CalculatorMoles of solute per kilogram of solvent.
- Dilution CalculatorC1V1 = C2V2 — stock and water to use.
- PPM CalculatorParts per million, ppb and percent.
- Ideal Gas Law CalculatorSolve PV = nRT for any one variable.
- Combined Gas Law CalculatorSolve P1V1/T1 = P2V2/T2.
- Partial Pressure CalculatorDalton’s law for gas mixtures.
- Graham’s Law CalculatorRelative rates of effusion.
- Freezing Point Depression CalculatorFreezing and boiling points of solutions.
- Osmotic Pressure CalculatorΠ = iMRT in atm and mm Hg.
- Activation Energy CalculatorArrhenius equation from two rate constants.
- Gibbs Free Energy CalculatorΔG = ΔH − TΔS and spontaneity.
- Nernst Equation CalculatorCell potential from E° and Q.
- Beer–Lambert Law CalculatorAbsorbance and concentration.
- pH CalculatorpH and pOH from ion concentration, and back.
- Buffer pH CalculatorHenderson–Hasselbalch buffer pH.
- Titration CalculatorUnknown concentration from a titration.
- Molar Mass CalculatorMolar mass and percent composition of a formula.
- Grams to Moles CalculatorGrams to moles and back, with molecules.
- Percent Yield CalculatorPercent yield of a reaction.
- Carbon Dating CalculatorRadiocarbon age from carbon-14.
- Chemical Equation BalancerBalance any reaction with whole numbers.
- Empirical Formula CalculatorFormula from percent composition.
- Limiting Reactant CalculatorLimiting reactant, theoretical yield and excess.
- Rydberg Equation CalculatorHydrogen spectral lines: wavelength and photon energy.
- Clausius-Clapeyron CalculatorVapor pressure, boiling point or ΔHvap from two points.
- Serial Dilution CalculatorTransfer and diluent volumes and each tube’s concentration.
- Integrated Rate Law CalculatorZero, first and second order: [A], time, half-life, k.
- Electron Configuration CalculatorFull and noble-gas configuration of any element.
- Stoichiometry CalculatorMoles, grams and gas volume of every substance in a reaction.
- Average Atomic Mass CalculatorWeighted mass from isotopes, or abundances from the average.
- Equilibrium Constant CalculatorK or Q with the shift direction, Kc to Kp, combined reactions, K and ΔG°.
- Enthalpy of Reaction CalculatorΔH° from enthalpies of formation, heat for your amount, and Hess’s law.
- ICE Table CalculatorEquilibrium amounts from K and starting amounts, K from data, and weak acid or base pH.
- Ksp and Solubility CalculatorKsp from solubility, solubility from Ksp, common ion effect and precipitation test, with a Ksp table.
- Doubling Time CalculatorBacterial doubling time, generations and growth rate from two cell counts.
- DNA Melting Temperature CalculatorOligo Tm by the Wallace rule or basic formula, GC content and molecular weight.
- Michaelis-Menten CalculatorEnzyme rate, substrate needed, and Vmax and Km fitted from your data.
- Cell Count CalculatorHemocytometer counts to cells per mL, trypan blue viability and seeding volume.
Tech & networking
Subnets, storage, bitrates, uptime and passwords.
- Subnet CalculatorIPv4 network, broadcast and host range from an address and prefix, plus subnet splits.
- RAID CalculatorUsable capacity and drive failures survived for RAID 0, 1, 5, 6 and 10.
- File Size & Bitrate CalculatorVideo and audio file size from bitrate and length, or the bitrate for a target size.
- Uptime CalculatorAvailability nines to downtime, plus series and parallel availability and error budget.
- Password Entropy CalculatorBits of entropy of a random password or passphrase, and the time to guess it.
- Hex CalculatorHex, decimal, binary and octal arithmetic with AND, OR, XOR, shifts and flags.
- Morse Code TranslatorText to Morse code and back with the ITU table, plus transmit time at any speed in words per minute.
- Caesar Cipher CalculatorEncode and decode the Caesar cipher, ROT13 and Vigenère, or try all 25 shifts.
- Check Digit CalculatorValidate or find the check digit of Luhn, ISBN-10, ISBN-13, UPC, EAN and IBAN numbers.
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