Energy Converter
Convert between joules, calories, kWh, kcal, BTU and more — instantly.
Result
Result
4.1840
How it works
Every energy conversion routes through the joule, the SI unit, which lets units from completely different worlds be compared: food calories, electricity kilowatt-hours, heating BTU and mechanical joules all measure the same physical quantity. The key factors: 1 kcal = 4.184 kJ, 1 kWh = 3.6 million joules, 1 BTU = 1,055 joules. Note the food trap — the "calorie" on a nutrition label is really a kilocalorie, a thousand of the physicist's calories, and the capital C in Calorie is the only clue. Those factors make surprising comparisons possible. A 2,000 kcal daily diet is about 8.4 MJ, or roughly 2.3 kWh — about what a washing machine cycle uses. It is the same energy accounting whether it powers a body or a motor.
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Frequently asked questions
How many kJ are in 1 kcal?
1 kcal = 4.184 kJ.
How many joules in 1 kWh?
1 kWh = 3,600,000 J (3.6 MJ).
Why do labels show both kJ and kcal?
Because the kilojoule is the official SI unit while the kilocalorie is what people actually recognise. Many food-labelling rules therefore require both, with kJ first. Divide kJ by 4.184 to get the familiar number.
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