Watt-hours to Kilojoules
Convert watt-hours to kilojoules instantly. 1 Wh = 3.6 kJ. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert watt-hours to kilojoules
To convert watt-hours to kilojoules, multiply by 3.6. The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
kJ = Wh × 3.6
Watt-hours to Kilojoules conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Watt-hours | Kilojoules |
|---|---|
| 1 Wh | 3.6 kJ |
| 2 Wh | 7.2 kJ |
| 3 Wh | 10.8 kJ |
| 5 Wh | 18 kJ |
| 10 Wh | 36 kJ |
| 20 Wh | 72 kJ |
| 25 Wh | 90 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |
| 500 Wh | 1,800 kJ |
| 1,000 Wh | 3,600 kJ |
What is a watt-hour?
One watt sustained for one hour. Battery capacity is quoted this way.
What is a kilojoule?
A thousand joules. Food energy is labelled in kilojoules outside the US.
The formula
kJ = Wh × 3.6
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Watt-hours to Kilojoules
- Type the number of watt-hours you want to convert.
- Read the result in kilojoules straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked kilojoules to watt-hours page.
Watt-hours to Kilojoules — frequently asked questions
How many kilojoules are in a watt-hour?
One watt-hour equals 3.6 kJ. kJ = Wh × 3.6
What is the formula to convert watt-hours to kilojoules?
The formula is kJ = Wh × 3.6. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert kilojoules back to watt-hours?
Divide instead of multiplying: one kilojoule is 0.2777777778 Wh. The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this watt-hours to kilojoules free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the watt-hours to kilojoules.
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 19, 2026 · Calculation runs client-side · No data collected · Report an error