A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules.
Watt hours to Kilojoules
Convert Watt-hour (Wh) to Kilojoule (kJ) instantly with an exact formula, conversion table, and FAQ.
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Convert watt hours (Wh) to kilojoules (kJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
kJ = Wh × 3.6
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Formula
kJ = Wh × 3.6
Wh = kJ × 0.2777777778
Conversion table
| 1 Wh | 3.600000 kJ |
| 5 Wh | 18 kJ |
| 10 Wh | 36 kJ |
| 20 Wh | 72 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |
| 500 Wh | 1800 kJ |
| 1000 Wh | 3600 kJ |
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How the formula works
Both watt-hour and kilojoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in watt hours by 3.6 to get kilojoules. To reverse the conversion, multiply a kilojoule value by 0.2777777778 to get back to watt hours.
Frequently asked questions
What is Watt-hour (Wh)?
A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules.
What is Kilojoule (kJ)?
A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
How do I convert watt hours to kilojoules?
Multiply the watt-hour value by 3.6 to get the equivalent in kilojoules. For example, 5 Wh × 3.6 = 18 kJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 3.6 is an exact, non-rounded value.
Can I convert kilojoules back to watt hours?
Yes. Divide the kilojoule value by 3.6, or multiply it by 0.2777777778, to get watt hours.
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About converting watt hours to kilojoules
A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules. A kilojoule (kJ) equals 1,000 joules and is commonly used on nutrition labels outside the United States.
Use this calculator to move between watt hours and kilojoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.