Energy Converter
Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, electronvolts, and foot-pounds. Every conversion uses exact definitional factors.
Quick Converter
Result
1 J = 0.239006 cal
cal = J × 0.2390057361376673
About Energy Units
Energy is the capacity to do work. Its SI unit is the joule, defined as the work done when a force of one newton acts over a distance of one meter. Many other units remain in daily use, and some (like the calorie and the kilowatt-hour) are widely known in fields as different as nutrition and electricity billing.
Key exact relationships
- 1 joule = 1 N·m = 1 kg·m²/s² exactly
- 1 thermochemical calorie = 4.184 J exactly
- 1 kilocalorie (food Calorie) = 4184 J exactly
- 1 watt-hour = 3600 J exactly
- 1 kilowatt-hour = 3,600,000 J exactly
- 1 BTU (International Table) = 1055.05585262 J exactly
- 1 electronvolt = 1.602176634 × 10⁻¹⁹ J exactly (2019 SI definition)
- 1 foot-pound = 1.3558179483314004 J exactly
Food calories vs. calories
Nutritional labels use "Calories" (capital C) which are really kilocalories. One food Calorie = 1000 small calories = 4184 joules. M-Convert uses the thermochemical calorie (4.184 J) throughout; this matches the value used in nutritional science.