What is the difference between calories and kilocalories?
In the United States the amount of energy stored in foods is expressed in kilocalories (kcal). A kilocalorie is equal to 1000 calories. However, the word Calorie (Cal) usually with a capital C is commonly used in place of kilocalories when referring to food energy. Internationally, most countries express food energy in kilojoules (kJ). One kilocalorie is equivalent to 4.2 kilojoules.
In the U.S., energy in foods is expressed in kilocalories (kcal). The scientific definition of a kilocalorie is the amount of energy needed to raise the temperature of 1 kilogram of water one degree Celsius from 15 to 16 at one atmosphere. The true calorie, sometimes referred to as a “small calorie,” is the amount of energy needed to raise the temperature of one gram of water one degree Celsius from 15 to 16 at one atmosphere. A kilocalorie is equal to 1000 calories. While the term “calorie” technically applies to the “small calorie,” in common usage, such as in reference to food energy, the term “calorie” is actually a kilocalorie. Internationally, most countries express food energy in kilojoules (kJ). One kcal equals 4.184 kJ. The USDA Nutrient Database for Standard Reference contains values for both kilocalories and kilojoules.
