Heating, Cooling & Electrical Calculators
Size air conditioners, furnaces, fans and water heaters, water pipes and pumps, wires, breakers and conduit, and see what your appliances, heating and electricity cost to run.
64 calculators · A–Z of all calculators
- 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.
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