The watt-hour
The watt-hour (Wh) equals 3,600 joules — the energy delivered by one watt of power over one hour. It is the natural unit for batteries, small electronics, and short-duration electrical loads.
Watt-hours to Kilojoules Converter
1 Wh = 3.6 kJ
1 watt-hour equals 3.6 kilojoules. To convert watt-hours to kilojoules, multiply the watt-hour value by 3.6. For quick reference: 1 Wh = 3.6 kJ, 5 Wh = 18 kJ, 10 Wh = 36 kJ, 100 Wh = 360 kJ.
Formula
Kilojoules = Watt-hours × 3.6Quick
How to convert watt-hours to kilojoules
Take your value
Start with your value in watt-hours.
Multiply by 3.6
Multiply the watt-hour value by 3.6. This is the exact conversion factor from watt-hours to kilojoules.
Read the result
The product is your value in kilojoules. For example, 5 Wh × 3.6 = 18 kJ.
Conversion formula
The exact factor from watt-hours to kilojoules is 3.6.
Kilojoules = Watt-hours × 3.6
Watt-hours to Kilojoules conversion table
Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.
| Watt-hours (Wh) | Kilojoules (kJ) |
|---|---|
| 0.001 Wh | 0.0036 kJ |
| 0.01 Wh | 0.036 kJ |
| 0.1 Wh | 0.36 kJ |
| 0.5 Wh | 1.8 kJ |
| 1 Wh | 3.6 kJ |
| 1.5 Wh | 5.4 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 |
| 250 Wh | 900 kJ |
| 500 Wh | 1800 kJ |
| 1000 Wh | 3600 kJ |
| 2000 Wh | 7200 kJ |
| 2500 Wh | 9000 kJ |
| 3600 Wh | 12960 kJ |
| 5000 Wh | 18000 kJ |
| 7500 Wh | 27000 kJ |
| 10000 Wh | 36000 kJ |
| 25000 Wh | 90000 kJ |
| 50000 Wh | 180000 kJ |
| 100000 Wh | 360000 kJ |
| 250000 Wh | 900000 kJ |
| 500000 Wh | 1800000 kJ |
| 1000000 Wh | 3600000 kJ |
| 2000000 Wh | 7200000 kJ |
| 3600000 Wh | 12960000 kJ |
| 5000000 Wh | 18000000 kJ |
| 10000000 Wh | 36000000 kJ |
| 25000000 Wh | 90000000 kJ |
| 50000000 Wh | 180000000 kJ |
| 100000000 Wh | 360000000 kJ |
| 250000000 Wh | 900000000 kJ |
| 500000000 Wh | 1800000000 kJ |
| 1000000000 Wh | 3600000000 kJ |
| 2000000000 Wh | 7200000000 kJ |
| 5000000000 Wh | 18000000000 kJ |
| 10000000000 Wh | 36000000000 kJ |
| 20000000000 Wh | 72000000000 kJ |
| 50000000000 Wh | 180000000000 kJ |
| 100000000000 Wh | 360000000000 kJ |
| 1000000000000 Wh | 3600000000000 kJ |
| 10000000000000 Wh | 36000000000000 kJ |
| 100000000000000 Wh | 360000000000000 kJ |
| 1000000000000000 Wh | 3.6000 × 10^15 kJ |
| 10000000000000000 Wh | 3.6000 × 10^16 kJ |
| 100000000000000000 Wh | 3.6000 × 10^17 kJ |
Real-world reference
A typical smartphone battery stores about 15 Wh. An LED bulb uses 8 Wh per hour of operation. In kilojoules, that gives you: 1 Wh = 3.6 kJ, 10 Wh = 36 kJ, 100 Wh = 360 kJ.
Frequently asked questions
- How many kilojoules are in 1 watt-hour?
- 1 watt-hour equals 3.6 kilojoules.
- How do I convert watt-hours to kilojoules?
- Multiply the watt-hour value by 3.6. So x Wh × 3.6 = the equivalent in kJ.
- What is 5 watt-hours in kilojoules?
- 5 watt-hours equals 18 kilojoules.
- What is 10 watt-hours in kilojoules?
- 10 watt-hours equals 36 kilojoules.
- What is 100 watt-hours in kilojoules?
- 100 watt-hours equals 360 kilojoules.
- How do I convert back from kilojoules to watt-hours?
- Multiply the kilojoule value by 0.277778. For example, 1 kJ = 0.277778 Wh.
- Is the watt-hour bigger than the kilojoule?
- Yes. 1 watt-hour is larger than 1 kilojoule — specifically 3.6 times larger.
- Are these conversion factors exact?
- Yes. The factor of 3.6 is derived directly from the SI definitions of watt-hour and kilojoule.
About the watt-hour and the kilojoule
The kilojoule
The kilojoule (kJ) equals exactly 1,000 joules. It is the standard unit on EU and many non-US nutrition labels — 1 dietary calorie ≈ 4.184 kJ. It also appears in industrial-process specifications and energy-storage ratings.