kWh to MJ converter
1 kWh is exactly 3.6 MJ, and 1 MJ is about 0.2778 kWh. Type in either box and the other one follows.
1 kWh = 3.6 MJ · 1 MJ ≈ 0.2778 kWh
Why 3.6?
A watt is one joule per second, so a kilowatt is 1,000 joules per second. An hour has 3,600 seconds. Keep 1 kW running for an hour and you have used 1,000 × 3,600 = 3,600,000 joules, which is 3.6 MJ. The factor follows straight from the definitions, so it's exact. Going the other way, 1 MJ is 1 ÷ 3.6 ≈ 0.2778 kWh.
On the napkin
A 2 kW kettle that runs for three minutes uses 2 × 0.05 = 0.1 kWh, or 0.36 MJ. That boils water for three or four cups of tea.
Scale it up to a year and the numbers get big. An average Dutch home takes about 2,500 kWh of electricity from the grid in a year. That's 9,000 MJ, or 9 GJ. Dutch heat networks bill in GJ. This sum lets you put your heat price per GJ next to your electricity or gas price per kWh.
Common values
| kWh | MJ |
|---|---|
| 1 | 3.6 |
| 10 | 36 |
| 100 | 360 |
| 1,000 | 3,600 |
| 2,500 | 9,000 |
| MJ | kWh |
|---|---|
| 1 | 0.2778 |
| 10 | 2.778 |
| 100 | 27.78 |
| 1,000 | 277.8 |
Need another unit?
The full energy converter shows any amount in every energy and power unit at once, from joules to therms to cups of tea.
Want this in a spreadsheet?
I'll email you two free ones: the converter for every energy unit, and a heat pump versus gas boiler check using your own bill. One short email a month at most.
Send me bothSources: the watt and the joule are SI units (BIPM, The International System of Units); 1 kWh = 3.6 MJ by definition. Dutch home: CBS StatLine 81528NED, average electricity delivered per dwelling, 2023 (provisional). Cup of tea: 250 ml from 15 °C to 100 °C with 10% kettle losses, as in the full converter.
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