What does kilocalorie mean?
A kilocalorie (kcal) is a metric unit of energy equal to 1,000 small calories. Conventionally, it is the amount of heat needed to raise the temperature of 1 kilogram of water by 1 degree Celsius. In nutrition, it is the formal measure of the energy supplied by food and is frequently used in dietary calculations, exercise estimates, and food labelling. Nutritionists and food manufacturers may call it a “Calorie,” with a capital C, or simply use “calorie” in less technical contexts. These larger units are the ones people usually mean when they discuss how many calories a meal contains. The word is useful when greater precision matters, as when distinguishing a scientific calorie from the dietary unit or converting energy values into joules. It measures quantity of energy rather than nutritional quality, so a food's kilocalorie content does not by itself indicate how healthy it is.
nounA unit of energy equal to 1,000 small calories, equivalent to the amount of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius. In nutrition, it is the formal unit for expressing the energy content of food.
- A unit of energy equal to 1,000 small calories, used especially in nutrition, metabolism, and the measurement of food energy.
"The meal contains approximately 650 kilocalories."
"Walking briskly for 30 minutes can expend around 200 kilocalories, depending on a person's size and pace."
"The laboratory measured the reaction's energy output and reported it as 15.4 kilocalories."
The standard plural is “kilocalories,” abbreviated “kcal.”
"The athlete consumed an additional 500 kilocalories after training."
That “250 Calories” on a food label is usually 250 kilocalories—not 250 tiny scientific calories.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kilocalorie come from?
Kilocalorie is formed by combining the metric prefix kilo-, meaning thousand, with calorie. The word calorie ultimately comes through French from Latin calor, meaning “heat,” and was developed as a scientific unit of heat before being applied to food energy. The prefixed form kilocalorie became established in scientific and nutritional measurement for a thousand calories.
Related word forms
How kilocalorie is actually used
The abbreviated form “kcal” is common in scientific, dietary, and nutritional contexts. In everyday discussion of food, speakers often say “calorie” even when they technically mean the larger dietary unit.
Easily confused with kilocalorie
A small calorie is one hundredth of a kilocalorie, but nutritional labels generally use the word “calorie” to mean the larger dietary unit.