How the calculator works
Electricity is billed in kilowatt-hours (kWh). One kWh is 1,000 watts running for one hour. The calculator multiplies an appliance's wattage by the hours it runs each day and the days it runs each month, then divides by 1,000 to get monthly kWh. It multiplies that by your price per kWh to get the monthly cost, and by 12 for the yearly cost.
If you know the yearly kWh from the yellow EnergyGuide label instead, switch the appliance to “kWh per year”. The calculator divides by 12 for a month and skips the watts-and-hours step.
Worked example: a space heater
You run a 1,500-watt space heater on high for 6 hours a night, every night for a 30-day month, and you pay $0.25 per kWh.
- Energy: 1,500 W × 6 hours × 30 days ÷ 1,000 = 270 kWh.
- Monthly cost: 270 kWh × $0.25 = $67.50.
- A full winter of five such months costs about $337.50.
The same heater costs much less at a lower rate. At the July 2026 U.S. average of 18.31 cents, 270 kWh costs about $49. At New York's average of 29.90 cents, it costs about $81. That is why the price you enter matters as much as the wattage.
Average electricity prices
| Area | Cents per kWh | 1,000 W for 1 hour |
|---|---|---|
| U.S. average | 18.31 | $0.18 |
| New York | 29.90 | $0.30 |
| New Jersey | 25.19 | $0.25 |
| Connecticut | 24.16 | $0.24 |
| California | 33.61 | $0.34 |
| Texas | 15.88 | $0.16 |
| Florida | 15.03 | $0.15 |
These are one summer month's averages across all utilities in a state. Prices change month to month and differ between utilities, so your own bill is the best source. Divide the bill total, including delivery charges, by the kWh used.
Upgrade payback
To check whether a more efficient model is worth it, the calculator takes the yearly kWh of the appliance you pick and subtracts the new model's label kWh. It multiplies the saving by your rate, then divides the extra price of the new model by that yearly saving. Example: an old refrigerator using 600 kWh a year replaced by one using 400 kWh saves 200 kWh, or $50 a year at $0.25. If the efficient model costs $250 more, it pays back in 5 years.
ENERGY STAR says certified refrigerators are about 9% more efficient than models that just meet the federal minimum standard. The EIA found that the most-used refrigerator in a home cost about $87 on average to run in 2020.
Edge cases
- Seasonal use. The yearly figure is the monthly figure × 12. For a heater or AC you only use part of the year, multiply the monthly cost by the months you actually run it.
- Tiered or time-of-use rates. Some utilities charge more per kWh above a usage tier or at peak hours. Use the rate for when you actually run the appliance.
- Standby power. Many electronics draw a little power when “off”. Enter those hours separately if you want to include them.
- Renters. If electricity is included in your rent, the landlord pays, but your use still matters if utilities are split among roommates. See the utility bill split calculator.
What to do next
If cooling is your biggest cost, size the unit correctly with the room AC BTU calculator. Look for state and utility incentives in our guide to energy upgrades and rebates, and build replacement costs into your plan with the home maintenance budget calculator.