Electricity cost calculator
Enter the appliance wattage, how long it runs and your rate from your bill. The rate starts at the US residential average from the EIA; replace it with your own.
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How the cost is worked out
Cost = watts × hours ÷ 1000 × rate ($/kWh)Example: a 1,500 W space heater running 4 hours a day for 30 days uses 1.5 × 4 × 30 = 180 kWh. At 18.2 ¢/kWh that's $32.76 for the month.
Getting an accurate answer
- Use your own rate. The default is the U.S. residential average forecast for 2026 in the EIA's September 2026 Short-Term Energy Outlook. State averages range widely. Divide the per-kWh charges on your bill by the kWh used.
- Nameplate watts are a maximum. Refrigerators, heaters and air conditioners cycle on and off with the thermostat, so their average is well below the label. A plug-in energy meter gives the real kWh.
- Time-of-use plans charge more at peak times. Run the calculation once per rate period.
For a whole-house estimate with several appliances, use the electric bill calculator.
Questions people ask
How do I calculate the cost of running an appliance?
Cost = watts × hours ÷ 1000 × rate per kWh. A 1,500 W heater for 6 hours at 18 ¢/kWh costs 1.5 × 6 × 0.18 = $1.62.
How much does it cost to run a space heater?
A 1,500 W heater at full power uses 1.5 kWh an hour. At the EIA 2026 US residential average of about 18 ¢/kWh that is roughly 27 ¢ an hour. Thermostat cycling usually lowers the real figure.
Where do I find my electricity rate?
On your bill, divide the total energy charges by the kWh used. Include delivery charges that are billed per kWh, but not fixed monthly fees.