Energy Converter - Convert Joules, Calories, kWh, BTU and More
Convert between energy units: Joules, Kilojoules, Calories, kWh, BTU, Electronvolts, and more
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Joule (J)
1
Kilojoule (kJ)
0.001
Calorie (cal)
0.239006
Kilocalorie (kcal)
0.000239006
Watt-hour (Wh)
0.000277778
Kilowatt-hour (kWh)
0.0000002778
BTU (British Thermal Unit)
0.000947817
Electronvolt (eV)
6,242,000,000,000,000,000
Foot-pound (ft·lb)
0.737562
How to Use
1Enter the energy value you want to convert
2Select the source unit (from)
3View conversions to all other energy units instantly
4Use the table to find your target unit
Frequently Asked Questions
One thermochemical calorie equals approximately 4.184 joules. One food calorie (kilocalorie) equals 4,184 joules or 4.184 kilojoules. This is why nutritional energy is typically expressed in kilocalories (kcal).
A calorie (cal) is the energy needed to raise 1 gram of water by 1°C. A kilocalorie (kcal) is 1,000 calories. Food labels use 'Calories' (with capital C) which actually refers to kilocalories.
1 kilowatt-hour (kWh) = 3,600,000 joules (3.6 megajoules). This is because 1 watt = 1 joule/second, so 1 kWh = 1000W × 3600s = 3,600,000 joules.
BTU (British Thermal Unit) is the amount of energy needed to raise 1 pound of water by 1°F at sea level. 1 BTU equals approximately 1,055 joules or 0.293 watt-hours.