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This electricity cost calculator shows how much it costs to run any appliance. Enter the appliance’s wattage, how many hours a day you use it and your electricity rate, and it calculates the energy used in kilowatt-hours (kWh) and the cost per hour, day, month and year.
How to Use the Electricity Cost Calculator
- Find the appliance’s power in watts on its label or in the manual. If only amps are listed, multiply amps by volts (120 V in the US, 230 V in the UK and Europe).
- Enter how many hours a day and how many days a month you use it.
- Enter your electricity rate per kWh from your bill. The default is the current US average.
Electricity Cost Formula
kWh = Watts × Hours ÷ 1,000
Cost = kWh × Rate per kWh
A kilowatt-hour is 1,000 watts used for one hour. Your utility bills you per kWh, so converting an appliance’s watts into kWh is the key step.
Example
A 1,500 W space heater used 4 hours a day for 30 days uses 1,500 × 4 ÷ 1,000 = 6 kWh a day, or 180 kWh a month. At 18.2¢ per kWh that costs about $32.76 a month, or $393 a year.
Typical Appliance Wattage
| Appliance | Typical watts | Cost per hour at 18.2¢/kWh |
|---|---|---|
| LED light bulb | 10 | $0.002 |
| Laptop | 50 | $0.009 |
| Ceiling fan | 75 | $0.014 |
| Flat-screen TV | 120 | $0.022 |
| Refrigerator (average while running) | 150 | $0.027 |
| Desktop computer | 200 | $0.036 |
| Window AC (10,000 BTU) | 1,000 | $0.182 |
| Microwave | 1,200 | $0.218 |
| Space heater | 1,500 | $0.273 |
| Hair dryer | 1,800 | $0.328 |
| Electric oven | 2,400 | $0.437 |
| Central AC (3 ton) | 3,500 | $0.637 |
| Electric clothes dryer | 5,000 | $0.910 |
Appliances with thermostats or compressors, such as refrigerators, heaters and air conditioners, cycle on and off, so their real running hours are often lower than the hours they are switched on.
Average Electricity Rates
The US average residential price was 18.2¢ per kWh in August 2026 according to EIA data, up 3.4% from a year earlier. Rates vary a lot by state, from roughly 11¢ to more than 40¢ per kWh, so use the rate from your own bill for the most accurate answer. The calculator works with any currency.
Ways to Cut Running Costs
- Swap incandescent bulbs for LEDs, which use about 75–85% less energy.
- Use timers and smart plugs to stop standby use.
- Improve attic insulation with our insulation calculator to reduce heating and cooling loads.
- Offset your usage with solar; see the solar panel calculator.
Sources
Frequently Asked Questions
How do I calculate the cost of running an appliance?
Multiply the appliance’s watts by the hours used and divide by 1,000 to get kWh, then multiply by your electricity rate per kWh.
How much does it cost to run a 1,500 watt heater?
At 18.2¢ per kWh, a 1,500 W heater costs about 27¢ per hour, or about $33 a month at 4 hours a day.
How many kWh does a house use per month?
The average US home uses roughly 850–900 kWh a month, but it varies widely with climate, home size and heating type.
How do I convert amps to watts?
Multiply amps by volts. A 10 amp appliance on a 120 V circuit draws about 1,200 watts.
Read the guide: How Much Does It Cost to Run a Space Heater?
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