Calorie (Cal for short), transliterated from English Calorie, is defined as the heat required to raise 1 gram of water to 1 degree Celsius at 1 atmospheric pressure; Calorie is an energy unit, which is still widely used in nutrition measurement and fitness manual. The international standard unit of energy is joule.

Calories, kilocalories, calories and kilojoules are all units of heat, and the conversion between them is:

1 calorie = 1 calorie =4. 186 joules;

1 kcal = 1 kcal = 1000 kcal = 1000 calories =4 186 joules =4. 186 kj.