Electricity cost calculator
Enter an appliance's wattage, how many hours a day you run it, and your electricity rate to see exactly what it costs per day, month, and year.
Total cost
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Per day
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Per month
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Per year
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Energy used: — kWh/day • — kWh total
Formula
kWh per day = watts / 1,000 × hours per day
Total kWh = kWh per day × days
Cost = total kWh × rate per kWh
Common appliance wattages
| Appliance | Typical watts |
|---|---|
| LED bulb | 9–12 W |
| Laptop | 45–65 W |
| Desktop PC + monitor | 150–300 W |
| Refrigerator | 100–200 W |
| Electric oven | 2,000–5,000 W |
| Space heater | 750–1,500 W |
| Air conditioner (window) | 500–1,500 W |
| Clothes dryer | 4,000–5,000 W |
Frequently asked
How is electricity cost calculated?
Cost = watts ÷ 1,000 × hours × days × rate per kWh. Power in kilowatts times hours gives kilowatt-hours (kWh), which is what your utility bills you for.
Where do I find my electricity rate?
Look at your electricity bill for the rate in cents per kWh. The US average is about $0.13/kWh, but rates vary widely by state and provider.
How much does it cost to run a 60-watt bulb for a month?
A 60W bulb running 8 hours a day for 30 days uses 14.4 kWh. At $0.13/kWh that's about $1.87/month.
How do I convert watts to kilowatts?
Divide watts by 1,000. A 1,500W space heater is 1.5 kW.
How do I share my calculation?
Click "Share with my numbers" to copy a URL that reopens with your exact inputs.