Kilojoules to Watt-hours
Convert kilojoules to watt-hours instantly. 1 kJ = 0.2777777778 Wh. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert kilojoules to watt-hours
To convert kilojoules to watt-hours, divide by 3.6 (multiply by 0.2777777778). 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.
Wh = kJ × 0.2777777778
Kilojoules to Watt-hours conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Kilojoules | Watt-hours |
|---|---|
| 1 kJ | 0.277778 Wh |
| 2 kJ | 0.555556 Wh |
| 3 kJ | 0.833333 Wh |
| 5 kJ | 1.388889 Wh |
| 10 kJ | 2.777778 Wh |
| 20 kJ | 5.555556 Wh |
| 25 kJ | 6.944444 Wh |
| 50 kJ | 13.888889 Wh |
| 100 kJ | 27.777778 Wh |
| 500 kJ | 138.888889 Wh |
| 1,000 kJ | 277.777778 Wh |
What is a kilojoule?
A thousand joules. Food energy is labelled in kilojoules outside the US.
What is a watt-hour?
One watt sustained for one hour. Battery capacity is quoted this way.
The formula
Wh = kJ × 0.2777777778
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 Kilojoules to Watt-hours
- Type the number of kilojoules you want to convert.
- Read the result in watt-hours 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 watt-hours to kilojoules page.
Kilojoules to Watt-hours — frequently asked questions
How many watt-hours are in a kilojoule?
One kilojoule equals 0.2777777778 Wh. Wh = kJ × 0.2777777778
What is the formula to convert kilojoules to watt-hours?
The formula is Wh = kJ × 0.2777777778. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert watt-hours back to kilojoules?
Divide instead of multiplying: one watt-hour is 3.6 kJ. 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 kilojoules to watt-hours 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 kilojoules to watt-hours.
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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