This article is about units of energy. For other uses, see food energy and calorie (disambiguation) The name calorie is used for two units of energy: the small calorie or gram calorie which is the approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius; large calorie, kilocalorie, kilogram calorie, dietary calorie, nutritionist’s calorie or food calorie, equal to 1000 small calories.