WattPeekWatts to kWh: calculate energy from power and time
Watts describe power at a moment. Kilowatt-hours describe energy used over time. To get kWh, you need both power and duration.
The formula
kWh = watts ÷ 1,000 × hours| Power | Time | Energy |
|---|---|---|
| 100 W | 10 hours | 1 kWh |
| 500 W | 2 hours | 1 kWh |
| 2,000 W | 30 minutes | 1 kWh |
Convert minutes first
Divide minutes by 60. For example, 15 minutes is 0.25 hours. A constant 1,000 W input for 15 minutes uses 0.25 kWh.
Which wattage should I enter?
Use average electrical input power for the period you are measuring. A maximum rating is not a measurement of everyday usage. If the appliance switches on and off, measured kWh is often the clearer input.
From energy to cost
Multiply kWh by your own price per kWh. At an illustrative price of 0.25, 1 kWh costs 0.25 currency units. The calculator performs both steps for you.
Open electricity calculator ↗