kWh to Watts Calculator
kWh to watts finds the average power of a load from the energy it used: watts equal kilowatt-hours times 1000 divided by the hours. Enter the kWh from your meter or bill and the time it covers, and the calculator shows average watts and kilowatts, with the formula and a table of common cases.
kWh to watts
500 W
P = E ÷ t → 1.5 kWh ÷ 3 h = 0.5 kW = 500 W.
How to convert kWh to watts
A kilowatt-hour is energy: one kilowatt used for one hour, exactly 3.6 million joules (BIPM, The International System of Units, 9th edition, 2019). A watt is power, energy per second. To get average power, divide the energy by the time: P(W) = E(kWh) × 1000 ÷ t(h).
Worked example: 1.5 kWh over 3 hours
1.5 kWh × 1000 = 1500 Wh. 1500 Wh ÷ 3 h = 500 W, or 0.5 kW. A device that really drew 500 W for the whole time would use that much; a device that cycled on and off would show the same average.
Worked example: a month on the bill
A bill showing 30 kWh used by one appliance across a 30-day month (720 hours) is an average of 30 × 1000 ÷ 720 = 41.67 W. That says nothing about the peak, only the average.
kWh to watts table
| Energy (kWh) | Time (hours) | Average watts | Average kilowatts |
|---|---|---|---|
| 0.1 | 1 | 100 | 0.1 |
| 0.25 | 1 | 250 | 0.25 |
| 0.5 | 1 | 500 | 0.5 |
| 1 | 1 | 1000 | 1 |
| 1 | 2 | 500 | 0.5 |
| 1.5 | 3 | 500 | 0.5 |
| 2 | 4 | 500 | 0.5 |
| 3 | 5 | 600 | 0.6 |
| 5 | 10 | 500 | 0.5 |
| 8 | 24 | 333.33 | 0.3333 |
| 10 | 24 | 416.67 | 0.4167 |
| 12 | 24 | 500 | 0.5 |
| 30 | 720 | 41.67 | 0.0417 |
Energy and power are not the same
People often write “kW” when they mean “kWh”. Remember: kilowatts (kW) are how fast energy is used right now, while kilowatt-hours (kWh) are how much was used over a period, like the distance and the speed of a car. If you know the watts and want the amps, use the watts to amps calculator.
Related converters
See also amps to watts and milliamps to amps, or return to the MicroCoulomb home page.
Frequently asked questions
How do you convert kWh to watts?
Multiply kilowatt-hours by 1000 to get watt-hours, then divide by the hours: watts = kWh × 1000 ÷ hours.
Can I convert kWh to watts without the time?
No. Energy needs a time to become power. 1 kWh over 1 hour is 1000 W; over 10 hours it is 100 W.
How many watts is 1 kWh per hour?
1 kWh used in 1 hour is an average of 1000 W, or 1 kW.
What is the difference between kW and kWh?
kW is power, the rate of use. kWh is energy, the total used over time.
Updated