Convert Kilojoules to Kilowatt-hours
Kilojoules to kilowatt-hours is the conversion you need when an energy figure is in kJ but you think in the unit on your electric bill. One kilojoule is approximately 0.0002777777777777778 kilowatt-hours, so the kilowatt-hour figure always comes out much smaller.
Kilojoules to Kilowatt-hours conversion table
| Kilojoules (kJ) | Kilowatt-hours (kWh) |
|---|---|
| 1 | 0.000278 |
| 2 | 0.000556 |
| 3 | 0.000833 |
| 5 | 0.001389 |
| 10 | 0.002778 |
| 20 | 0.005556 |
| 50 | 0.013889 |
| 100 | 0.027778 |
| 500 | 0.138889 |
| 1,000 | 0.277778 |
The formula
To convert kilojoules to kilowatt-hours, multiply the number of kilojoules by 0.0002777777777777778:
kilowatt-hours = kilojoules × 0.0002777777777777778
A worked example
Say you have 3600 kJ and want it in kilowatt-hours:
3600 × 0.0002777777777777778 = 1 kWh
So 3600 kilojoules is exactly 1 kilowatt-hour.
Why it's an approximation
The factor 0.0002777777777777778 is a rounded value. A kilowatt-hour is one kilowatt of power held for a full hour, and an hour is 3600 seconds, so a kilowatt-hour is exactly 3600 kilojoules. Going the other way means dividing by 3600, and one 3600th is a repeating decimal — roughly 0.000277778 — so the everyday factor is rounded. Whole kilowatt-hours still come out exact because the 3600 relationship underneath is exact.
When you'll use it
Putting an energy figure given in kilojoules into the kilowatt-hours your electric bill uses, sizing a battery or appliance against its rated energy, or comparing the energy in a fuel or food figure to what a device draws from the wall.
Frequently asked questions
How many kilojoules are in a kilowatt-hour?
Exactly 3600. A kilowatt-hour is a kilowatt held for one hour, and an hour is 3600 seconds, so it works out to 3600 kilojoules.
How many kilowatt-hours are in a kilojoule?
About 0.0002777777777777778 kilowatt-hours — roughly 0.000277778. It's a rounded figure because it's one 3600th, which repeats past the decimal point.
Is the kilojoules to kilowatt-hours conversion exact?
The factor is approximately 0.0002777777777777778, rounded for everyday use since it's a repeating decimal. But 3600 kJ is exactly 1 kWh, so round numbers of kilowatt-hours come out clean.