A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix.
Megajoules to Watt hours
Convert Megajoule (MJ) to Watt-hour (Wh) instantly with an exact formula, conversion table, and FAQ.
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Convert megajoules (MJ) to watt hours (Wh) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules.
Wh = MJ × 277.7777778
Results update instantly for Megajoules to Watt hours conversions.
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Formula
Wh = MJ × 277.7777778
MJ = Wh × 0.0036
Conversion table
| 1 MJ | 277.777778 Wh |
| 5 MJ | 1388.888889 Wh |
| 10 MJ | 2777.777778 Wh |
| 20 MJ | 5555.555556 Wh |
| 50 MJ | 13888.888889 Wh |
| 100 MJ | 27777.777778 Wh |
| 500 MJ | 138888.888889 Wh |
| 1000 MJ | 277777.777778 Wh |
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How the formula works
Both megajoule and watt-hour measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in megajoules by 277.7777778 to get watt hours. To reverse the conversion, multiply a watt-hour value by 0.0036 to get back to megajoules.
Frequently asked questions
What is Megajoule (MJ)?
A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix.
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.
How do I convert megajoules to watt hours?
Multiply the megajoule value by 277.7777778 to get the equivalent in watt hours. For example, 5 MJ × 277.7777778 = 1388.888889 Wh.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 277.7777778 is an exact, non-rounded value.
Can I convert watt hours back to megajoules?
Yes. Divide the watt-hour value by 277.7777778, or multiply it by 0.0036, to get megajoules.
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About converting megajoules to watt hours
A megajoule (MJ) is a metric-prefixed unit of energy equal to 106 joules, using the SI mega prefix. A watt-hour (Wh) is the energy delivered by one watt of power sustained for one hour, equal to 3,600 joules.
Use this calculator to move between megajoules and watt hours accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.