Electricity cost calculator: what does it cost to run?
Enter the appliance’s watts, how long it runs and the price per kWh from your bill. You get kWh and cost per hour, day, month and year.
Enter your measurements
More options: Days/yr
- Cost per hour
- $0.26
- Cost per month (average)
- $62.05
- Cost per year
- $744.60
- Energy per day
- 12 kWh
- Energy per year
- 4,380 kWh
1,500 W ÷ 1,000 = 1.5 kW × $0.17/kWh = $0.26 an hour
1.5 kW × 8 h = 12 kWh × $0.17 = $2.04 a day
12 kWh × 365 days = 4,380 kWh a year = $744.60 ($62.05 a month)
Quick answers for common sizes
| Example | Answer |
|---|---|
| The cost to run a space heater | $0.26 an hour at 17¢/kWh (1,500 W) |
| The cost to run a window AC unit | $0.17 an hour at 17¢/kWh (10,000 BTU) |
| The cost to run a dehumidifier | $1.60 a day at 17¢/kWh (12 hours) |
| The cost to run a ceiling fan | $0.15 a day at 17¢/kWh (12 hours) |
The same appliance at other hours per day
| Hours used per day | Energy per day | Cost per day | Cost per month (average) |
|---|---|---|---|
| 1 | 1.5 kWh | $0.26 | $7.76 |
| 2 | 3 kWh | $0.51 | $15.51 |
| 4 | 6 kWh | $1.02 | $31.03 |
| 8 | 12 kWh | $2.04 | $62.05 |
| 12 | 18 kWh | $3.06 | $93.08 |
| 24 | 36 kWh | $6.12 | $186.15 |
The four worked examples below cover the questions people ask most: the cost to run a space heater, the cost to run a window AC unit, the cost to run a dehumidifier and the cost to run a ceiling fan.
How the cost is worked out
Utilities bill by the kilowatt-hour (kWh): 1,000 watts running for one hour. Virginia Cooperative Extension’s method is to multiply the appliance’s watts by the hours it runs and divide by 1,000 for kWh, then multiply by your rate.
kWh per day = watts × hours per day ÷ 1,000 cost per day = kWh per day × price per kWh cost per year = kWh per day × days used × price per kWh
If the label lists amps instead of watts, multiply amps by the voltage — 120 V for most US household appliances, 240 V for big ones like dryers and cooktops.
Finding your price per kWh
The 17¢ default is only an example. Rates vary by utility, season and time of day, and your bill also carries fixed charges and delivery fees. For the most honest number, divide the bill’s total by the kWh it charges for; for comparing two appliances, the energy (kWh) column is what matters anyway.
Typical wattages
| Appliance | Typical watts |
|---|---|
| Space heater (portable) | 750–1,500 |
| Window AC, 5,000 BTU | 450–600 |
| Window AC, 10,000 BTU | 900–1,200 |
| Dehumidifier | 785 |
| Ceiling fan | 65–175 |
| Coffee maker | 900–1,200 |
| Microwave oven | 750–1,100 |
| Water heater (40 gallon) | 4,500–5,500 |
More appliances, with starting watts too, are on the appliance wattage chart.
Why your estimate and your bill disagree
- Thermostats. A heater set to 68 °F in a mild room may run a third of the time; the same heater in a drafty garage runs flat out.
- Settings. A heater’s low setting, a fan’s speed or an AC’s fan-only mode draws far less than the nameplate maximum.
- Standby. Many appliances draw a few watts when “off”; across a house these phantom loads add up.
- Fixed charges. Your bill’s monthly service charge doesn’t change whatever you run.
What you’ll need
- Plug-in electricity usage monitorBudget price
Plugs in between the wall and a 120 V appliance and shows real watts and kWh over a day — the honest way to fill in a load list, especially for fridges that cycle on and off.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How much does it cost to run a 1,500 watt heater for an hour?
It uses 1.5 kWh an hour, so at 17¢ per kWh it costs about 26¢ an hour. Multiply 1.5 by your own rate. Worked through on the cost to run a space heater.
How do I calculate kWh from watts?
Multiply watts by hours and divide by 1,000. A 100 W appliance running 10 hours uses 1 kWh.
Why is my appliance using less than the calculator says?
The label gives maximum watts. Thermostats, lower settings and cycling compressors mean most appliances average well below it. A plug-in usage monitor measures the real figure.
Does it cost more to run something on solar?
Once the system is paid for, the energy is free, but every kWh you use has to come from panels and batteries you bought — that is why off-grid systems are sized on watt-hours. See the solar payback calculator for the grid-tied side.
Related guides
Sources
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).