Watt-hours (W·h) to Megajoules (MJ) Conversion
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
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 (W·h) | Megajoules (MJ) |
|---|---|
| 0.1 W·h | 0.00036 MJ |
| 1 W·h | 0.0036 MJ |
| 2 W·h | 0.0072 MJ |
| 3 W·h | 0.0108 MJ |
| 5 W·h | 0.018 MJ |
| 10 W·h | 0.036 MJ |
| 20 W·h | 0.072 MJ |
| 30 W·h | 0.108 MJ |
| 50 W·h | 0.18 MJ |
| 100 W·h | 0.36 MJ |
| 1000 W·h | 3.60 MJ |
Frequently Asked Questions (FAQ)
How many megajoules are in 1 watt-hours?
1 watt-hours (W·h) is exactly 0.0036 megajoules (MJ).
How do I convert watt-hours to megajoules?
Multiply the value in watt-hours by 0.0036 to get the result in megajoules. Or use the converter above — type any number and see the result instantly.