Convert Kilojoules to Watt-hours
1 kilojoule is 0.277778 Wh. One kilojoule is exactly 0.277777777778 watt-hours.
One kilojoule is 0.27777778 watt-hours. To convert kilojoules to watt-hours, multiply by 0.27777778; to go the other way, divide by 0.27777778 or multiply by 3.6. The factor is exact rather than rounded: it follows from NIST Special Publication 811. A thousand joules.
Factor checked against the defining standard · How we check
- Kilojoules × 0.27777778
value * 0.2777777777780.278 Wh
1 kilojoule in every energy unit
| Unit | Value | Exact factor |
|---|---|---|
| joules | 1,000 J | × 1,000 |
| kilojoules (as entered) | 1 kJ | — |
| calories | 239.0057361 cal | × 239.005736138 |
| kilocalories | 0.2390057361 kcal | × 0.239005736138 |
| watt-hours | 0.2777777778 Wh | × 0.277777777778 |
| kilowatt-hours | 0.0002777777778 kWh | × 0.000277777777778 |
| British thermal units | 0.9478171203 BTU | × 0.947817120313 |
| foot-pounds | 737.5621493 ft·lbf | × 737.562149277 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert kilojoules to watt-hours?
- 1.Take the measurement in kilojoules.
- 2.Multiply by 0.27777778 — that is how many watt-hours fit in one kilojoule.
- 3.To go back the other way, divide by 0.27777778, or multiply by 3.6.
Worked example: 25 kilojoules to watt-hours
- Formula
- kJ × 0.27777778 = Wh
- Arithmetic
- 25 × 0.27777778 = 6.944444 Wh
- Answer
- 25 kJ = 6.944444 Wh
The factor is rounded for display; the figure above is computed from the full value.
Kilojoules to watt-hours conversion table
| Kilojoules | Watt-hours |
|---|---|
| 1 kJ | 0.277778 Wh |
| 2 kJ | 0.555556 Wh |
| 3 kJ | 0.833333 Wh |
| 4 kJ | 1.111111 Wh |
| 5 kJ | 1.388889 Wh |
| 6 kJ | 1.666667 Wh |
| 7 kJ | 1.944444 Wh |
| 8 kJ | 2.222222 Wh |
| 9 kJ | 2.5 Wh |
| 10 kJ | 2.777778 Wh |
| 12 kJ | 3.333333 Wh |
| 15 kJ | 4.166667 Wh |
| 20 kJ | 5.555556 Wh |
| 25 kJ | 6.944444 Wh |
| 50 kJ | 13.888889 Wh |
| 100 kJ | 27.777778 Wh |
| 200 kJ | 55.555556 Wh |
| 300 kJ | 83.333333 Wh |
| 500 kJ | 138.888889 Wh |
| 1000 kJ | 277.777778 Wh |
| 2000 kJ | 555.555556 Wh |
| 5000 kJ | 1,388.888889 Wh |
| 10000 kJ | 2,777.777778 Wh |
What is a kilojoule?
A thousand joules. Food energy outside the US is labelled here, alongside or instead of calories.
What is a watt-hour?
One watt sustained for an hour, so exactly 3,600 joules. Battery capacity is quoted here because it is an amount of energy rather than a rate.
How many watt-hours are in a kilojoule?
One kilojoule is 0.27777778 watt-hours. Going the other way, one watt-hour is 3.6 kilojoules. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every energy unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Joules | J | the base unit |
| Kilojoules | kJ | 1000 joule |
| Calories | cal | 4.184 joule |
| Kilocalories | kcal | 4184 joule |
| Watt-hours | Wh | 3600 joule |
| Kilowatt-hours | kWh | 3600000 joule |
| British thermal units | BTU | 1055.0559 joule |
| Foot-pounds | ft·lbf | 1.3558179 joule |
Source: NIST Special Publication 811 — the thermochemical calorie is exactly 4.184 J
Questions people actually ask
- How many watt-hours are in a kilojoule?
- 0.27777778. One watt sustained for an hour, so exactly 3,600 joules. Battery capacity is quoted here because it is an amount of energy rather than a rate.
- How do I convert watt-hours back to kilojoules?
- Divide by 0.27777778, or multiply by 3.6 — they are the same operation.
Other energy conversions
Watt-hours to kilojoules — the same conversion the other way.