Kilowatts (kW) measure power; kilowatt-hours (kWh) measure energy used over time. Enter a power rating and a run time and this converts kW to kWh, then shows the totals if you run it daily.
The two units are easy to mix up. A 2kW heater is rated at 2 kilowatts of power; run it for 3 hours and it uses 2 × 3 = 6 kWh of energy. If your appliance is rated in watts rather than kilowatts, divide by 1,000 first, or use the watts to kWh calculator. To turn the kWh into money, see kWh to cost.
Common questions
What is the difference between kW and kWh?
A kilowatt (kW) is a rate of power, like the speed of a car. A kilowatt-hour (kWh) is the energy used over time, like the distance travelled. A 1kW device running for 1 hour uses 1 kWh.
How many kWh is 2kW for an hour?
Exactly 2 kWh. Kilowatt-hours are the power in kilowatts multiplied by the hours, so 2kW for 1 hour is 2 kWh, and for 30 minutes it is 1 kWh.