Energy Converter
Convert between energy units including Joule (J), Kilojoule (kJ), Calorie (cal), Kilocalorie (kcal), Kilowatt-hour (kWh), BTU, and more.
Energy Converter
Convert between energy units. All conversions use joule (J) as the base SI unit.
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Understanding Energy Units
Energy is the capacity to do work. The SI unit of energy is the Joule (J), but many other units are used across different fields including nutrition, electricity, and engineering.
Common Energy Units:
- Joule (J): SI base unit of energy — 1 J = 1 kg·m²/s²
- Kilojoule (kJ): 1,000 joules — used in food energy labeling outside the US
- Calorie (cal): Energy to raise 1 g of water by 1°C — used in chemistry
- Kilocalorie (kcal): 1,000 calories — the “food calorie” used in nutrition
- Kilowatt-hour (kWh): Energy unit used for electricity billing, 1 kWh = 3,600,000 J
- BTU: British Thermal Unit — used in HVAC and heating systems in the US
Key Conversions:
- 1 kcal = 4,184 J = 4.184 kJ
- 1 kWh = 3,600,000 J = 3,600 kJ = 860 kcal
- 1 BTU = 1,055 J ≈ 0.252 kcal
- 1 kJ = 0.239 kcal