Convert between joules, calories, kilowatt-hours, BTU, and other energy units.
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Convert between different energy units including joules, calories, kilowatt-hours, BTU, and more. Essential for physics, engineering, nutrition, and power calculations. Get instant conversions between any energy units.
| Unit | Abbreviation | To Joules | Common Use |
|---|---|---|---|
| Joule | J | 1 | SI energy unit |
| Calorie | cal | 4.184 | Food energy |
| Kilowatt-hour | kWh | 3,600,000 | Electricity bills |
| BTU | BTU | 1,055.06 | Heating/cooling |
| Erg | erg | 0.0000001 | CGS unit |
1 kilocalorie (kcal) = 1,000 calories. Food labels list kilocalories but call them "calories." So a 100-calorie snack is actually 100 kcal or 100,000 cal.
1 kWh = 3,600,000 joules (3.6 megajoules). This is the amount of energy used by a 1,000W device running for 1 hour.
BTU (British Thermal Unit) is mainly used in the US for heating and cooling. It measures the energy needed to raise 1 pound of water by 1°F.