kWh to joules, MJ and therms
Convert energy between kilowatt hours, megajoules, joules, therms and British thermal units.
Factors from the NIST Guide to the SI.
Show the workings
| Step | Sum | Answer |
|---|---|---|
| In megajoules | 1 kWh × 3.6 MJ | 3.6 MJ |
| In MJ | 3.6 MJ ÷ 1 MJ | 3.6 MJ |
What this leaves out or assumes
- A therm here is the therm used for UK gas. A US therm is very slightly smaller.
Where the figures come from
- Megajoules in one kilowatt hour: 3.6 megajoules. Source: NIST Guide to the SI, Appendix B.8: factors for units listed alphabetically. Checked 13 November 2026.
Energy unit conversions
| Unit | In kWh | In MJ |
|---|---|---|
| 1 kilowatt hour (kWh) | 1 | 3.6 |
| 1 megajoule (MJ) | 0.2778 | 1 |
| 1 therm | 29.307 | 105.506 |
| 1,000 BTU | 0.2931 | 1.0551 |
A kilowatt hour is the energy of 1,000 watts for an hour: 1,000 × 3,600 seconds = 3.6 million joules, or 3.6 megajoules. One kWh is about 3,412 BTU. Energy bills are in kWh; older gas bills and some boiler specifications use therms or BTU.
To turn gas meter readings into kWh, use the gas units to kWh calculator, which also corrects for temperature and pressure.