Energy Converters
Convert between joules, calories, kilojoules, kWh, and BTU.
Energy is the capacity to do work, measured in joules in the SI system. Related units include the kilojoule and the food calorie (1 kcal = 4.184 kJ), the kilowatt-hour used on electric bills (1 kWh = 3.6 million joules), and the BTU used in heating and cooling. Converting between these units is a fixed multiplication because they all measure the same physical quantity. Note that a food 'Calorie' (capital C) is actually a kilocalorie — 1,000 small calories.
Reviewed August 2026
5 Converters
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