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Energy
Watt-hours to Megajoules
Convert watt-hours (Wh) to megajoules (MJ). Type a value below to see the result update instantly. Reference table and formula included.
Calculator
1 Wh = 0.0036 MJ
Watt-hours to Megajoules Conversion Table
Common values, ready to copy:
| watt-hours | megajoules |
|---|---|
| 1 Wh | 0.0036 MJ |
| 2 Wh | 0.0072 MJ |
| 5 Wh | 0.018 MJ |
| 10 Wh | 0.036 MJ |
| 25 Wh | 0.09 MJ |
| 50 Wh | 0.18 MJ |
| 100 Wh | 0.36 MJ |
| 1,000 Wh | 3.6 MJ |
Formula
megajoules = watt-hours × 0.0036
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
About Watt-hours and Megajoules
Watt-hours (Wh): The energy consumed by a 1-watt device in 1 hour; equals 3,600 joules. Common uses: Small battery capacities (laptop batteries are typically 40-100 Wh), and lighting energy use.
Megajoules (MJ): A million joules; the unit for larger-scale energy quantities. Common uses: Daily food intake (a typical adult consumes 8-10 MJ per day), fuel energy content (gasoline ≈ 34 MJ per liter), and industrial energy.
How the conversion works
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
The exact relationship is megajoules = watt-hours × 0.0036, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.
When this conversion matters
Converting between watt-hours and megajoules comes up wherever energy measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.