Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU. Type in any field to update all others instantly.
| Reference | kJ | kcal | kWh |
|---|---|---|---|
| 1 dietary Calorie (food label) | 4.184 | 1 | 0.00116 |
| Apple (~95 kcal) | 397 | 95 | 0.11 |
| Daily adult intake (~2000 kcal) | 8368 | 2000 | 2.326 |
| 1 kWh (electricity) | 3600 | 860 | 1 |
| Litre of petrol (~34 MJ) | 34000 | 8124 | 9.44 |
An energy converter translates a quantity of work or heat between different unit systems. The joule (J) is the SI unit. The calorie (cal) and kilocalorie (kcal) measure heat and food energy. The watt-hour (Wh) and kilowatt-hour (kWh) measure electrical energy. The BTU (British Thermal Unit) is used in heating and cooling systems, especially in the US.
1 kcal (kilocalorie) = 1000 cal (small calories). Food labels always use kcal —the "Calorie" on packaging is actually a kilocalorie.
1 kWh = 3,600,000 J = 3.6 MJ.
BTU (British Thermal Unit) is the energy needed to heat 1 pound of water by 1°F. 1 BTU = 1055.06 J.
Multiply kcal by 4184. For example, 100 kcal = 418,400 J = 418.4 kJ.