Electric bill calculator

How to work out what an appliance costs

Your utility bills you for kilowatt-hours (kWh): 1,000 watts running for one hour. Turn any appliance into kWh and you can price it. This is the method the Department of Energy teaches, and the one the calculator runs. Here it is for the central air conditioner in the default list.

1. 1

   Find the watts

   Check the nameplate. If it only lists amps, multiply by the volts: 120 V for normal outlets, 240 V for big appliances. A 3-ton central AC draws about 3,000 W.

2. 2

   Multiply by hours per day, divide by 1,000

   3,000 W × 6 hours ÷ 1,000 = 18 kWh a day.

3. 3

   Multiply by days per month

   18 kWh × 30 days = 540 kWh a month.

4. 4

   Multiply by your rate

   540 kWh × $0.1816 (the U.S. average in August 2026) = $98.06 a month. Add up every appliance the same way: the default list comes to 792 kWh and $144 a month, or $1,727 a year.

One catch: things with a thermostat or compressor cycle on and off. A refrigerator plugged in all day only runs its compressor about a third of the time, so the DOE suggests counting 8 hours a day, not 24. The same logic applies to AC, freezers and water heaters: hours means hours actually running, not hours switched on.

Typical wattage and monthly use

These are the defaults in the calculator. Wattage varies with size, age and settings, so use the nameplate or a plug-in usage monitor when you can.

Electricity prices by state

Average residential price in August 2026, the latest month EIA has published, next to the same month a year earlier. The last column is how much the average home used per month in 2024. Tap a state to load its rate.

Rates swing with the season and by utility. These averages divide what utilities billed by the kWh they sold, so fixed customer charges are spread into the price. If your utility uses tiers or time-of-use pricing, your rate at 6 p.m. can be double the one at 2 a.m.

Where the money really goes

Lights and chargers feel like they matter, but they rarely do. Ten LED bulbs on for 5 hours a day use 13.5 kWh a month, under $2.50 at the national average. The big lines are anything that makes heat or removes it. In the default list, central air alone is 68% of the bill. An electric water heater, if you switch it on, adds 405 kWh a month, more than all the other default items besides the AC put together.

• Cooling and heating: the DOE says setting the thermostat back 7 to 10°F for 8 hours a day can save up to 10% a year on heating and cooling. A smart or programmable thermostat does it for you. Clean or replace the filter, and keep the outdoor unit clear.
• Water heating: set the tank to 120°F, fix drips and wash clothes in cold water. When the tank dies, a heat pump water heater is two to three times as efficient as a standard electric one, per the DOE.
• Laundry: the dryer is the costly half. Full loads, a clean lint filter and a clear vent all shorten run time. Line-drying even some loads cuts the cost directly.
• Space heaters: fine for one room for an hour, expensive as a main heat source. Four hours a day at 1,500 W is 180 kWh a month.
• Old fridges and freezers: a second fridge in a hot garage works hard. If it's more than 15 years old, plug it into a usage monitor for a week and price it here.

Anything on 240 volts, like a dryer, range, water heater or EV charger, should be installed or rewired by a licensed electrician. Plug-in monitors only work on 120-volt outlets. For whole-home tracking, an electrician can add a panel monitor.

Check the estimate against your bill

Your bill is the best reality check. Find the kWh used this period and the total charged, then divide dollars by kWh. That is your true rate, fees and taxes included. Type it in the rate box above.

Next, compare kWh. Most bills show the last 12 months as a bar chart. Pick a month with the same weather as the one you modeled. If the calculator comes in well under the bill, something big is missing: often an electric furnace or heat pump, a well pump, a second fridge or a water heater you thought was gas. If it comes in well over, you probably overestimated AC or heater hours.

For a single appliance, a plug-in usage monitor settles it. Leave it on a fridge or freezer for a full week, divide the kWh by 7 and multiply by 30. Then put the real number in the calculator by adjusting the hours.

Sources and assumptions

• State rates: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, average residential price for August 2026 (released October 23, 2026). 2026 values are preliminary.
• Average use per home: EIA, Electric Sales, Revenue, and Average Price, Table 5A, data year 2024 (U.S.: 863 kWh and $142.26 a month).
• Method and refrigerator duty cycle: U.S. Department of Energy, Estimating Appliance and Home Electronic Energy Use.
• Thermostat setback and water heater figures: DOE Energy Saver, Programmable Thermostats and Heat Pump Water Heaters.
• Default wattages are typical running watts for common U.S. models, not a single published standard. Compare models with ENERGY STAR's product finder. The calculator ignores standby power, fixed monthly fees and taxes unless you fold them into your own rate.

Common questions