Energy Converter
Convert between joules, kWh, Wh, calories, kilocalories and BTU. Free, fast and easy to use.
All units
| Joule | 3,600,000 J |
|---|---|
| Kilojoule | 3,600 kJ |
| Megajoule | 3.6 MJ |
| Watt-hour | 1,000 Wh |
| Kilowatt-hour | 1 kWh |
| Megawatt-hour | 0.001 MWh |
| Calorie | 860,420.65 cal |
| Kilocalorie | 860.42065 kcal |
| British thermal unit | 3,412.1416 BTU |
How it works
Choose the units and type a value. One kilowatt-hour is 3.6 megajoules – the energy a 1 kW appliance uses in one hour. One kilocalorie (the “calorie” on food labels) is 4.184 kJ, and one BTU is about 1,055 J.
Worked examples
- 1 kWh = 3.6 MJ
- 2,000 kcal = 2.3244444 kWh
- 1 BTU = 1.0550559 kJ
Calculations run locally in your browser. Results are for information only — for engineering, electrical or financial decisions, verify the assumptions and applicable standards.
Frequently asked questions
How many joules are in a kWh?
3,600,000 joules (3.6 MJ), because one watt is one joule per second.
Are food calories the same as kcal?
Yes. The “calories” on food labels are kilocalories: 1 kcal = 4.184 kJ.