Electricity cost calculator
Enter a device’s power, how long it runs and your electricity price to see what it costs per day, month and year.
Cost per year
How it works
kWh per day = watts × hours ÷ 1000cost = kWh × price per kWhWorked example
- 100 W × 4 h = 400 Wh = 0.4 kWh a day
- 0.4 × 0.30 = 0.12 a day
- × 365 = 43.80 a year
Frequently asked questions
Where do I find the power in watts?
On the label or in the manual. It is the maximum; many devices use less on average (a fridge cycles on and off). A plug-in power meter shows the real use.
What is a kWh?
A kilowatt-hour: 1,000 watts for one hour. Electricity bills charge per kWh, so a 2,000 W heater running for 3 hours uses 6 kWh.
What does standby cost?
Enter the standby power (often 0.5–5 W) and 24 hours a day to see it; a few watts all year can cost more than people expect.