Megajoules (MJ) to Watt-hours (W·h) Conversion
Megajoules
The megajoule (MJ) is a unit of energy equal to exactly 1,000,000 joules (10⁶ J). It is used in energy policy, engineering, and physics for large-scale energy quantities. One kilowatt-hour (kWh) equals exactly 3.6 MJ — the conversion fundamental to understanding electricity bills. A litre of petrol contains approximately 34 MJ of chemical energy. The explosive yield of conventional explosives is sometimes expressed in megajoules.
Watt-hours
The watt-hour (W·h) is a unit of energy equal to exactly 3,600 joules, defined as the energy consumed by a one-watt device operating for one hour. It is used in electrical engineering and consumer electronics for expressing battery capacities: a smartphone battery typically holds 10–20 Wh. In aviation, aircraft battery capacities are specified in watt-hours for international transport regulations (lithium batteries above 100 Wh face restrictions).
| Megajoules (MJ) | Watt-hours (W·h) |
|---|---|
| 0.1 MJ | 27.7778 W·h |
| 1 MJ | 277.7778 W·h |
| 2 MJ | 555.5556 W·h |
| 3 MJ | 833.3333 W·h |
| 5 MJ | 1,388.8889 W·h |
| 10 MJ | 2,777.7778 W·h |
| 20 MJ | 5,555.5556 W·h |
| 30 MJ | 8,333.3333 W·h |
| 50 MJ | 13,888.8889 W·h |
| 100 MJ | 27,777.7778 W·h |
| 1000 MJ | 277,777.7778 W·h |
Frequently Asked Questions (FAQ)
How many watt-hours are in 1 megajoules?
1 megajoules (MJ) is exactly 277.778 watt-hours (W·h).
How do I convert megajoules to watt-hours?
Multiply the value in megajoules by 277.778 to get the result in watt-hours. Or use the converter above — type any number and see the result instantly.