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 Megajoules
Convert Watt-hour (Wh) to Megajoule (MJ) instantly with an exact formula, conversion table, and FAQ.
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Convert watt hours (Wh) to megajoules (MJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix.
MJ = Wh × 0.0036
Results update instantly for Watt hours to Megajoules conversions.
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Formula
MJ = Wh × 0.0036
Wh = MJ × 277.7777778
Conversion table
| 1 Wh | 0.003600 MJ |
| 5 Wh | 0.018000 MJ |
| 10 Wh | 0.036000 MJ |
| 20 Wh | 0.072000 MJ |
| 50 Wh | 0.180000 MJ |
| 100 Wh | 0.360000 MJ |
| 500 Wh | 1.800000 MJ |
| 1000 Wh | 3.600000 MJ |
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How the formula works
Both watt-hour and megajoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in watt hours by 0.0036 to get megajoules. To reverse the conversion, multiply a megajoule value by 277.7777778 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 Megajoule (MJ)?
A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix.
How do I convert watt hours to megajoules?
Multiply the watt-hour value by 0.0036 to get the equivalent in megajoules. For example, 5 Wh × 0.0036 = 0.018000 MJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 0.0036 is an exact, non-rounded value.
Can I convert megajoules back to watt hours?
Yes. Divide the megajoule value by 0.0036, or multiply it by 277.7777778, to get watt hours.
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About converting watt hours to megajoules
A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules. A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix.
Use this calculator to move between watt hours and megajoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.