Converters
Energy Converter
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Convert between energy units: joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and electronvolts. Free, instant, no signup.
Conversions
Joules (J)1,000
Kilojoules (kJ)1
Calories (cal)239.0057
Kilocalories (kcal)0.2390057
Watt-hours (Wh)0.2777778
Kilowatt-hours (kWh)0.0002777778
BTU (British Thermal Units)0.9478134
Electronvolts (eV)6.2415e+21
1 kcal (food Calorie) = 4,184 J. 1 kWh = 3.6 MJ. 1 BTU ≈ 1,055 J. Electronvolts are used in atomic and particle physics.
How to Convert Joules to Calories (2026)
How to Convert Joules to Calories — free online tool and guide with examples.