Appliance Electricity Cost Calculator
Quick answer: A 1,500 W space heater running 4 hours a day uses 6 kWh daily and 2,190 kWh yearly, costing $400.77/year at 18.3 cents/kWh. The formula is kWh = watts x hours / 1,000 and cost = kWh x rate — the calculator applies it to your appliance with an editable rate.
What does that appliance really cost to run? This appliance electricity cost calculator turns wattage and usage hours into daily, monthly, and yearly energy use in kWh and dollars, using the U.S. average residential rate (editable) of 18.3 cents/kWh.
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How to use this calculator
Enter the appliance's wattage from its nameplate, how many hours a day it runs, how many days a year, and your electricity rate in cents/kWh. The default 18.3 cents is the U.S. average — replace it with your own bill's rate for a personal figure. Results update instantly.
How this is calculated
This tool applies the standard energy-to-cost conversion. Formula: kWh per year = watts x hours/day x days/year / 1,000; cost = kWh x rate. Daily kWh = watts x hours/day / 1,000, and monthly figures use 365/12 days per month.
- Inputs: appliance wattage in watts (check the nameplate); hours used per day; days used per year; electricity rate in cents/kWh (editable).
- Assumptions: the appliance draws its rated wattage the whole time it runs; one flat rate applies all year; the rate you enter is what your utility charges per kWh.
- Edge cases: devices with cycling loads (fridges, AC) run at full wattage only part of the time — multiply by the duty cycle, or measure with a plug meter for an exact figure.
- Estimates: costs are labeled estimates because real usage varies and rates can be tiered or time-of-use; the default rate is the U.S. average, not your bill.
Reference data
| Figure | Value |
|---|---|
| U.S. average residential rate | 18.31 cents/kWh (July 2026 data) |
| EIA 2026 full-year average forecast | 18.21 cents/kWh |
| Lowest state average | Louisiana, 12.72 cents/kWh (July 2026) |
| Highest state average | Hawaii, 48.0 cents/kWh (July 2026) |
Sources: U.S. Energy Information Administration (EIA) Electric Power Monthly, July 2026 data, and Short-Term Energy Outlook (Oct 6, 2026). State rate comparison: https://homewattcheck.com/electricity-rates/.
Method & sources
Rate figures come from the U.S. Energy Information Administration (EIA) Electric Power Monthly, July 2026 data, and the Short-Term Energy Outlook (Oct 6, 2026), as embedded in the table above. The cost math itself is computed live from your inputs; no paid APIs or logins are involved.
Worked example
1,500 W space heater x 4 hours/day x 365 days, at 18.3 cents/kWh. Energy per year: 1,500 x 4 x 365 / 1,000 = 2,190 kWh. Cost per year: 2,190 x $0.183 = $400.77. Per day: 6 kWh = $1.10; per month: 182.5 kWh = $33.40.
Frequently asked questions
Why is 18.3 cents the default electricity rate?
The default matches the U.S. average residential electricity rate: 18.31 cents per kWh from the EIA's Electric Power Monthly (July 2026 data), with the EIA Short-Term Energy Outlook (Oct 6, 2026) forecasting an 18.21-cent average for 2026. Enter your own rate from your utility bill for a personal figure — state rates range from about 12.72 cents in Louisiana to 48.0 cents in Hawaii.
What is the difference between watts and watt-hours?
Watts (W) are power — how fast an appliance uses energy. Watt-hours (Wh) are energy — power over time: a 1,500 W heater running 4 hours uses 6,000 Wh, or 6 kWh. Your bill charges for kWh, which is why the formula divides by 1,000.
What about time-of-use rates?
Some utilities charge more during peak hours and less off-peak. This calculator uses one flat rate. If you are on time-of-use billing, enter the rate for the hours you run the appliance most, or run the calculation once per rate period and add them up.
Does standby (vampire) power matter?
It can. Many devices draw a few watts even when off — enter the standby wattage with 24 hours/day to see its yearly cost. A 5 W device on standby all year uses about 44 kWh (5 x 24 x 365 / 1,000), roughly $8 at the default rate (estimate).