How to use the electricity cost calculator
- Choose what you know. For most devices that's the wattage and how long you use it. Big appliances also carry a yellow EnergyGuide label with an estimated yearly kWh figure.
- Wattage, hours and days — for example, a hair dryer might run 1,500 watts for 10 minutes (0.17 hours) a day, 7 days a week.
- Electricity price — your rate in cents per kWh. Your bill's total divided by the kWh used gives an all-in rate that includes delivery charges.
The formula
The method below, published by Virginia Cooperative Extension in an appliance energy fact sheet developed with the U.S. Department of Energy, works for any appliance:
- Daily kWh = watts × hours used per day ÷ 1,000
- Yearly kWh = daily kWh × days used per year
- Yearly cost = yearly kWh × price per kWh
Example: a 1,000-watt appliance used 3 hours a day uses 3 kWh a day and 1,095 kWh a year. At the U.S. average of 18.31¢ per kWh, it costs $0.55 a day, $16.71 a month and $200.49 a year.
Typical appliance wattages
Nameplate wattages from the same fact sheet, with the cost of one hour at full power at 18.31¢ per kWh. The wattage on a label is the most the appliance draws; many run below it on lower settings.
| Appliance | Typical wattage | Cost per hour |
|---|---|---|
| Water heater (40 gallon) | 4,500–5,500 W | $0.82–$1.01 |
| Clothes dryer | 1,800–5,000 W | $0.33–$0.92 |
| Dishwasher (drying uses more) | 1,200–2,400 W | $0.22–$0.44 |
| Hair dryer | 1,200–1,875 W | $0.22–$0.34 |
| Clothes iron | 1,000–1,800 W | $0.18–$0.33 |
| Space heater (portable) | 750–1,500 W | $0.14–$0.27 |
| Vacuum cleaner | 1,000–1,440 W | $0.18–$0.26 |
| Toaster | 800–1,400 W | $0.15–$0.26 |
| Toaster oven | 1,225 W | $0.22 |
| Coffee maker | 900–1,200 W | $0.16–$0.22 |
| Microwave oven | 750–1,100 W | $0.14–$0.20 |
| Dehumidifier | 785 W | $0.14 |
| Refrigerator (frost-free, 16 cu. ft.) | 725 W | $0.13 |
| Clothes washer | 350–500 W | $0.06–$0.09 |
| Ceiling fan | 65–175 W | $0.01–$0.03 |
| Flat-screen TV | 120 W | $0.02 |
| Electric blanket (single / double) | 60–100 W | $0.01–$0.02 |
| Laptop computer | 50 W | $0.01 |
A refrigerator is plugged in all day but its compressor cycles on and off. The fact sheet suggests dividing the time it is plugged in by three to estimate the hours at full wattage, about 8 hours a day.
How to find an appliance's wattage
- Label or nameplate: usually on the back or bottom, or in the manual.
- Amps × volts: if only the current is listed, multiply amps by the voltage. Most U.S. appliances use 120 volts; large ones such as clothes dryers and electric cooktops use 240.
- EnergyGuide label: refrigerators, washers, water heaters and other major appliances show estimated yearly kWh; choose "kWh per year" above.
- Plug-in energy monitor: measures what a 120-volt device really uses over a day or a week, which is the most accurate way to size up something that cycles.
Electricity prices
The default price is the U.S. average residential price for July 2026, 18.31¢ per kWh, from the EIA's Electric Power Monthly (up from 17.45¢ a year earlier). State averages differ widely, so use your own rate for an exact answer. Many devices also draw a little power when switched off; unplugging them or using a power strip with a switch removes these "phantom loads."
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply the wattage by the hours used and divide by 1,000 to get kWh, then multiply by your price per kWh. A 1,500-watt heater running 4 hours uses 6 kWh, which costs $0.90 at 15¢ per kWh.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is 1,000 watts used for one hour. It is the unit on your electric bill: a 100-watt device running for 10 hours uses 1 kWh.
Which appliances use the most electricity?
Appliances that heat or cool draw the most power: water heaters, clothes dryers, space heaters, ovens and air conditioners. What you pay also depends on how many hours each one runs.
How do I convert amps to watts?
Multiply amps by volts. A device drawing 10 amps on a 120-volt outlet uses about 1,200 watts. Larger appliances on 240-volt circuits use twice the watts for the same amps.
Why is my bill higher than this estimate?
Your bill includes every device in the home, fixed customer charges, taxes and sometimes higher rates at peak times. Use your bill’s total divided by its kWh as the price for a more realistic estimate.
Last updated: October 8, 2026