Unit Converters
Energy Converter
Convert between joules, calories, kWh, and BTU.
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About the Energy Converter
Convert energy units free — joules to calories, calories to joules, kWh to joules, and BTU to kWh — across joules, kilojoules, calories, kilocalories (food calories), watt-hours, kilowatt-hours, BTU, and foot-pounds. Useful for nutrition labels (1 kcal = 4,184 J), electricity bills (1 kWh = 3.6 MJ), heating specs, and physics problems.
How to use the Energy Converter
- 01Enter a value.
- 02Pick the unit to convert from.
- 03Read every other unit and copy.
Frequently asked questions
How many joules in a calorie?
1 calorie = 4.184 joules; 1 kcal (food calorie) = 4,184 joules.
What is a kWh in joules?
1 kWh = 3,600,000 joules (3.6 MJ).
Are food calories the same as calories?
Food labels use kilocalories: 1 food Calorie = 1,000 small calories = 4,184 joules. A 2,000-Calorie diet is 2,000 kcal.