About the Energy Converter
Convert energy units for nutrition, electricity and heating: kcal to kJ, kWh to BTU and more.
Key features
- Convert joules, kilojoules, calories, kilocalories, Wh, kWh and BTU
- Food energy: kcal ↔ kJ
- Electricity: kWh ↔ MJ and BTU
- Swap direction with one click
- See the value in every unit at once
- Free, instant, no sign-up
Energy unit conversion
Energy is measured differently on food labels, electricity bills, gas bills and air conditioner specs. Convert between them to compare like with like.
Common conversions
| From | To | Multiply by |
|---|---|---|
| kcal | kJ | 4.184 |
| kJ | kcal | 0.239006 |
| kWh | MJ | 3.6 |
| kWh | BTU | 3,412.14 |
| BTU | J | 1,055.06 |
| Wh | J | 3,600 |
Food energy reference
| Food (approx.) | kcal | kJ |
|---|---|---|
| Medium apple | 95 | 397 |
| Slice of bread | 80 | 335 |
| Chocolate bar (50 g) | 250 | 1,046 |
| Daily intake (typical adult) | 2,000 | 8,368 |
Electricity examples
| Appliance | Energy |
|---|---|
| 10 W LED bulb for 10 hours | 0.1 kWh |
| 2 kW kettle for 3 minutes | 0.1 kWh |
| Electric car, 60 kWh battery | 216 MJ |
Power (watts) × time (hours) = energy (watt-hours).
Related calculators
Estimate your daily energy needs with the Calorie Calculator, or convert anything else with the Unit Converter.
How to use the Energy Converter
- Enter your numbers in the fields above. Units and options can be changed at any time.
- The result updates instantly as you type; there's no calculate button to press.
- Check the breakdown under the main result for the details behind the number.
- Adjust the inputs to compare scenarios, for example a different rate or term.