Convert Watt-hours to Kilojoules
One watt-hour equals 3.6 kilojoules. Type any value to convert watt-hours to kilojoules instantly — with a full reference table below.
Convert Watt-hours to Kilojoules
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How to convert Watt-hours to Kilojoules
To convert watt-hours to kilojoules, multiply by 3.6. One watt-hour equals 3.6 kJ, and one kilojoule equals 0.277778 Wh.
- Take the value in watt-hours — for example 7.5 Wh.
- Multiply by 3.6 (the number of kilojoules in one watt-hour).
- 7.5 × 3.6 = 27 kJ.
Quick mental estimate: Multiply the number of watt-hours by 3.6 — that is exact.
Watt-hours to Kilojoules conversion table
| Watt-hours | Kilojoules |
|---|---|
| 1 Wh | 3.6 kJ |
| 2 Wh | 7.2 kJ |
| 5 Wh | 18 kJ |
| 10 Wh | 36 kJ |
| 20 Wh | 72 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |
| 200 Wh | 720 kJ |
| 500 Wh | 1,800 kJ |
| 1,000 Wh | 3,600 kJ |
| 2,000 Wh | 7,200 kJ |
| Kilojoules | Watt-hours |
|---|---|
| 1 kJ | 0.277778 Wh |
| 2 kJ | 0.555556 Wh |
| 5 kJ | 1.388889 Wh |
| 10 kJ | 2.777778 Wh |
| 20 kJ | 5.555556 Wh |
| 50 kJ | 13.88889 Wh |
| 100 kJ | 27.77778 Wh |
| 200 kJ | 55.55556 Wh |
| 500 kJ | 138.8889 Wh |
| 1,000 kJ | 277.7778 Wh |
| 2,000 kJ | 555.5556 Wh |
About converting Watt-hours to Kilojoules
Watt-hours (Wh) and Kilojoules (kJ) are both units of energy. The exact factor is 1 Wh = 3.6 kJ, so multiply by 3.6 to go from watt-hours to kilojoules (or divide to go back).
The conversion runs entirely in your browser. Need the reverse? Use the Kilojoules to Watt-hours converter, or the full unit converter for every unit at once.
Real-world energy in watt-hours and kilojoules
| Example | Watt-hours | Kilojoules |
|---|---|---|
| One food Calorie (kcal) | 1.162222 Wh | 4.184 kJ |
| A 100 W bulb running for one hour | 100 Wh | 360 kJ |
| A smartphone battery (≈19 Wh) | ≈ 19.25 Wh | ≈ 69.3 kJ |
| A 2,000 kcal daily diet | 2,324.444 Wh | 8,368 kJ |
| One kilowatt-hour | 1,000 Wh | 3,600 kJ |
“≈” marks typical values; the rest are defined or measured figures.
The units
One watt for one hour: exactly 3,600 J.
Used for: Battery capacity (power banks, laptops).
1,000 joules.
Used for: Food energy on labels in Australia and the EU.
The thermochemical calorie is exactly 4.184 J and a kilowatt-hour is exactly 3.6 MJ, so these factors are exact.