[ Calorie, Cal., Kilocalorie, kcal., large calorie ]
A unit of measure of food energy. 1 kilocalorie (kcal) is equivalent to 4.184 kilojoules (KJ).
A “small calorie” (cal, 4.184 joules) is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius, at a pressure of one atmosphere.
A “large Calorie” is equivalent of 1000 small calories or 1 kcal. It is abbreviated to “Calorie” (Cal) with an upper-case C. It is chiefly used in North America.
In 1948 the Consultative Committee on Thermometry recommended discarding the calorie, because it could not be derived directly from basic units. In 1954, the Système International (SI) officially adapted the joule and in 1970, the Committee on Nomenclature of the American Institute of Nutrition advised that the kilocalorie should be replaced by the kilojoule (kJ) in scientific publications. Nonetheless, both the Calorie and the kilocalorie both persist today as a unit of food energy.