What does standby power cost you each year?

What standby power is and why it adds up

Standby power is the electricity a device uses while it is switched off or not doing its main job: the red light on a TV, the clock on a microwave, a charger with nothing attached, a speaker waiting for a voice command. Lawrence Berkeley National Laboratory (LBNL), which has tracked the subject for decades, says that nearly all new electrical products draw some, around the clock, and that in most developed countries it is typically 5–10% of residential electricity use. Most newer products use less than 0.5 watts. The trouble is that a home has dozens of them, and the few that stay half awake, such as set-top boxes, can draw much more than the rest.

The Department of Energy's Energy Saver Guide makes the same point in plain words: many consumer electronics keep drawing power even when switched off, which can add 5%–10% to the utility bill. This calculator turns your own list into kilowatt-hours and dollars, so you can see which two or three devices are worth unplugging.

The formula

For each device: kWh a year = standby watts × hours in standby per day × number of devices × 365 ÷ 1,000. The cost is the kWh times your price per kWh, and the CO₂ is the kWh times the national grid average, 770.884 lb CO₂e per MWh from EPA eGRID2023, or 0.35 kg per kWh. The "average watts" line under the answer is the total kWh converted back to a constant load, kWh × 1,000 ÷ 8,760 hours: a handy way to compare with a light bulb.

Hours: use 24 for devices that never leave standby. A TV that is on for four hours is in standby for the other 20, so enter 20, not 24; the hours the device is on are not standby and belong in the electricity cost calculator.

Worked example

Berkeley Lab's own rule of thumb: one watt all year is 8.76 kWh (LBNL rounds to 9 kWh), or $1.14 at 13¢ per kWh (LBNL: about $1.20). A 5-watt device is 43.8 kWh and $5.69. Now a small home: a set-top box at 8 watts for 20 hours a day, two game or streaming boxes at 3 watts, a soundbar at 2 watts and six chargers and adapters at 0.5 watts. The calculator gives 154.8 kWh a year, which is $26.67 at 17.23¢, the same as a 17.7-watt load running day and night, and about 54 kg of CO₂. That is real money but not a fortune: the savings come from the one or two devices at the top of the table, not from unplugging every charger.

Limits of this method

• The watts are yours. We do not offer a table of typical watts per device. Berkeley Lab publishes one as a spreadsheet, but measurements vary with the model, the year and the settings. A watt meter (Berkeley Lab says they cost under $50) beats any list.
• The famous national numbers are estimates. NRDC's 2015 report put idle loads at about $165 per household and $19 billion a year for the country, but it measured about 70,000 homes in northern California and extended the result; its definition also includes devices left active, not only low-power modes. The 5–10% share is Berkeley Lab's typical figure, not a guarantee for your house.
• Standby heat is not always wasted. In winter a few watts of electronics add a little heat to the room, and in summer they add to the cooling load. The calculator counts the electricity only.
• Price tiers. If your utility charges more for each additional kWh, the first kWh you save are the expensive ones, so the real saving can be higher than at the average rate.

How much does standby power cost per year?

It depends on the watts and on your rate. Berkeley Lab's rule: 1 watt left on all year is about 9 kWh (exactly 8.76 kWh), roughly $1.20 at 13 cents per kWh. A 5-watt device uses about 45 kWh a year (43.8 kWh by exact arithmetic) and costs about $6. At the 2025 US residential average of 17.23 cents per kWh, 1 watt costs $1.51 a year. Berkeley Lab adds that many small devices add up in a home with 40 or more products.

What share of my electric bill is standby power?

Berkeley Lab says standby is typically 5–10% of residential electricity use in most developed countries, and the Department of Energy's Energy Saver Guide says many electronics that draw power even when switched off can add 5%–10% to the utility bill. NRDC's 2015 'Home Idle Load' study put always-on idle devices at about $165 a year per US household, up to $440 on a top-tier utility rate, but that figure comes from meter data of northern California homes extended to the whole country, and it counts every device that stays on when not in use, not only standby modes. Your own home can be far lower or higher: measure it.

How do I measure the standby watts of a device?

Plug the device into a watt meter and the meter into the wall. Berkeley Lab says such meters are sold for under $50 and some libraries lend them. Put the device in the state you want to measure (off with the remote, sleeping, charger with nothing attached) and wait for the reading to settle. Meters are reasonably accurate, but Berkeley Lab warns that the error is relatively larger when the draw is below about 1 watt, so read a small device over a longer time or use the meter's kWh counter for a day. Many modern devices draw a bit more for a few minutes after plugging in, then drop.

Which devices are the worst offenders?

Anything that waits for a command or stays connected: TVs, game consoles, cable and satellite set-top boxes, soundbars, printers, desktop computers, smart speakers, and chargers left in the outlet. The Department of Energy's guide says an ENERGY STAR certified set-top box is 25% more efficient than a conventional one, which tells you where it sees room to improve. Berkeley Lab notes that most newer products draw less than 0.5 watts in standby, while products from twenty years ago typically drew 1 to 3 watts. The calculator does not guess: you enter the watts you measured.

Is it worth unplugging things or buying a smart power strip?

Worth it for the few devices that draw several watts and are hardly used, such as a second TV, a game console or a printer. A 5-watt device unplugged for the whole year saves about $7.55 at the national average price, so a power strip only pays for itself if it switches off several such devices; check its price against that number. Unplugging a 0.3-watt phone charger saves about $0.45 a year. The Department of Energy recommends advanced power strips that cut power to electronics that are not in use, and unplugging battery chargers when they are not in use.

How is the CO2 figure calculated?

We multiply the kilowatt-hours by the national average grid emission rate from the EPA's eGRID2023 data, 770.884 pounds of CO2-equivalent per megawatt-hour, which is 0.35 kg per kWh. It is an average over the whole US grid, measured at the power plant; your state's grid, and the plants that actually run when your devices draw power, can be cleaner or dirtier, and transmission losses are not included.

Sources: Lawrence Berkeley National Laboratory, Standby Power site (standby.lbl.gov, home page and Frequently Asked Questions, read October 28, 2026); U.S. Department of Energy, Energy Saver Guide 2022 (Home Office and Electronics); NRDC, Home Idle Load (May 2015); U.S. EIA, Electric Power Annual 2025, Table 2.4 (average residential price, 17.23¢ per kWh); U.S. EPA eGRID2023. Related tools: electricity cost calculator, LED savings calculator, carbon footprint calculator, solar panel calculator. How we check our calculators.