How to calculate what an appliance costs to run
Your utility bills you for energy in kilowatt-hours (kWh). An appliance's cost is just three numbers multiplied together: kilowatts × hours × price per kWh. Watts on a label divide by 1,000 to give kilowatts.
Worked example — a 1,500 W space heater for 8 hours: 1,500 ÷ 1,000 = 1.5 kW. 1.5 kW × 8 h = 12 kWh a day. At the U.S. average of 18.19¢ per kWh (Jan–Aug 2026, EIA) that is $2.18 a day, or $66.40 over a 30-day month.
Finding the watts
- Watts on the label — usually on a plate near the cord or on the back. That is the maximum the appliance draws.
- Only amps and volts? Multiply them: a 12.5 A heater on 120 V is 1,500 W. Nameplate amps are a ceiling, so the result is an upper bound.
- A yellow EnergyGuide label gives energy use in kWh per year from a federal test. Use that number directly — it already accounts for cycling. Ignore the label's dollar figure: it assumes 14¢ per kWh, and older labels assumed even less.
- Measure it. A plug-in meter (the Kill A Watt type handles up to 15 A) records real kWh over a few days. It's the only reliable answer for an old fridge, a dehumidifier or a PC.
Why the real cost is often lower than watts × hours
Anything with a thermostat or compressor switches itself on and off. A refrigerator's compressor, a space heater with a thermostat and an air conditioner all spend part of each hour idle. The calculator's time at full power field handles that: 100% for a kettle, hair dryer or EV charger, much less for cycling appliances. When you have a rated kWh-per-year figure, use it instead.
What common appliances cost a month
At the U.S. average price of 18.19¢/kWh, using the typical hours shown:
| Appliance | Assumed use | kWh / month | Cost / month |
|---|---|---|---|
| Refrigerator, French door | 557 kWh/yr rated | 46.4 | $8.44 |
| Electric water heater, 50 gal tank | 3,530 kWh/yr rated | 294.2 | $53.51 |
| Electric clothes dryer (vented) | 607 kWh/yr rated | 50.6 | $9.20 |
| Space heater, 1,500 W | 1,500 W × 8 h/day | 365 | $66.40 |
| Window AC, 8,000 BTU | 525 W × 8 h/day | 127.8 | $23.24 |
| Dehumidifier, portable (>30 pints) | 460 kWh/yr rated | 38.3 | $6.97 |
| TV, 55 inch | 93 W × 5 h/day | 14.1 | $2.57 |
| Gaming PC, mid-range (while gaming) | 400 W × 3 h/day | 36.5 | $6.64 |
| PlayStation 5 (gaming) | 215 W × 3 h/day | 19.6 | $3.57 |
| Wi-Fi router (24/7) | 10 W × 24 h/day | 7.3 | $1.33 |
| Ceiling fan, high speed | 35 W × 8 h/day | 8.5 | $1.55 |
| LED bulb (60 W equivalent) | 9 W × 5 h/day | 1.4 | $0.25 |
| EV charging, Level 2 (7.2 kW) | 7,200 W × 2 h/day | 438 | $79.68 |
Refrigerator, water heater, dryer and TV figures are ENERGY STAR certified averages; older or larger models can use considerably more. Heating and cooling dominate most bills: EIA's household survey attributes 19% of home electricity to air conditioning, 12% to space heating and 12% to water heating.
Which price per kWh to use
The calculator defaults to EIA's average residential price for your state — total residential revenue divided by kWh sold. Because it spreads delivery and fixed customer charges over every kWh, it is close to your all-in rate (total bill ÷ kWh used). Prices range from 12.46¢ in North Dakota to 46.41¢ in Hawaii so far in 2026. For the cost of adding one appliance, the more precise number is your marginal rate: add up only the per-kWh lines on your bill, since the fixed monthly charge doesn't change. See every state on the electricity rates by state page.
Common mistakes
- Mixing up kW and kWh. kW is how fast power is drawn; kWh is the amount used. A 1 kW heater running 3 hours uses 3 kWh.
- Using the power-supply rating. A 1,000 W PC power supply or a console's brick rating is a ceiling. Sony's own figures put a PS5 at roughly 200–220 W while gaming.
- Forgetting always-on loads. A device left on 24/7 runs 8,760 hours a year; 10 W of standby is 88 kWh.
- Trusting old wattage tables. Lists that put a fridge at 725 W or a ceiling fan at 65–175 W come from decades-old tables. Today's ENERGY STAR ceiling fans average 35 W on high.
For the biggest loads, use the dedicated calculators: space heater, air conditioner, EV charging, refrigerator, clothes dryer, dehumidifier, pool pump and hot tub. Thinking about solar? Start with the solar calculators.