Electricity running-cost calculator
This calculator works out how much it costs to run any electric appliance. Pick an appliance (or type its wattage), set the hours per day and the number of days, and choose your state — it applies the U.S. DOE formula cost = (watts ÷ 1000) × hours × days × rate and shows the cost per day, per month and per year. The default rate is the US average residential price of 18.56¢/kWh (March 2026, EIA). It runs entirely in your browser.
Source: EIA Electric Power Monthly, Table 5.6.A (residential). Data as of June 2026.
How it works
The formula is the one the Department of Energy publishes, and it's intentionally transparent:
daily kWh = (watts ÷ 1000) × hours per day
cost = daily kWh × days × (price in ¢ per kWh ÷ 100)
A kilowatt-hour (kWh) is one kilowatt of power used for one hour — it's the unit your utility bills you for. A 1,000 W appliance run for one hour uses exactly 1 kWh. See the methodology for the wattage sources and assumptions, the appliance pages for typical usage, and the state pages for local rates.
Frequently asked questions
How do you calculate the cost to run an appliance?
Use the U.S. Department of Energy formula: cost = (watts ÷ 1000) × hours per day × days × price per kWh. For example, a 1,500 W heater run 8 hours a day for 30 days uses 1.5 × 8 × 30 = 360 kWh, which at the US average 18.56¢/kWh costs about $67. The calculator does this for you and converts to per-day, per-month and per-year.
What electricity rate should I use?
Use the price on your own electricity bill (the "price per kWh"), which is the most accurate. If you don't have it handy, pick your state to use its EIA residential average, or leave it on the US average of 18.56¢/kWh (March 2026). Rates vary by utility, plan and time of day.
Where do the appliance wattages come from?
They are typical figures from the U.S. Department of Energy and ENERGY STAR-grade references, shown as ranges where appropriate. Your specific model's wattage is on its label or nameplate (or amps × volts); enter that for an exact result.
Does the calculator include standby (phantom) power?
No. It estimates the cost while the device is actively running for the hours you enter. Always-on standby draw is small per device but adds up across a home; for always-on devices like a fridge, enter 24 hours per day.
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Last updated: 2026-06-20