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Energy Converter
Convert between joules, calories, kilocalories, watt-hours, BTU, and more.
| Unit | Value |
|---|---|
| Joule (J) | 3600000 |
| Kilojoule (kJ) | 3600 |
| Megajoule (MJ) | 3.6 |
| Calorie (cal) | 860420.7 |
| Kilocalorie (kcal/Cal) | 860.4207 |
| Watt-hour (Wh) | 1000 |
| Kilowatt-hour (kWh) | 1 |
| BTU (British Thermal) | 3412.128 |
| Electronvolt (eV) | 2.2469e+25 |
Energy unit formulas
Energy units are related by fixed conversion factors. Use the calculator to convert any value instantly, or apply formulas directly:
- Joules to calories: 1 cal = 4.184 J.
- Kilocalories: 1 kcal = 1,000 cal = 4,184 J.
- Watt-hours: 1 Wh = 3,600 J, 1 kWh = 3,600,000 J.
- BTU: 1 BTU = 1,055.06 J.
Real-world energy examples
A 60 W bulb running for one hour uses 60 Wh, which is 216,000 joules. A 2,000 kcal meal contains about 8.37 MJ of energy.
A typical electric car battery stores around 60 kWh = 216 MJ. A single kWh is about the energy in 860 food calories.
An air conditioner rated at 12,000 BTU uses about 3.52 kWh for one hour of cooling, because 1 BTU = 1,055 J.
Frequently Asked Questions
A small calorie (cal) is the energy to raise 1g of water by 1°C. A food Calorie (Cal / kcal) = 1,000 small calories. When nutrition labels say 200 calories, they mean 200 kcal = 836,800 joules.