Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A kilocalorie (kcal) is a unit of energy equal to 1,000 calories, commonly used to measure the energy content in food and the amount of energy expended through physical activity. In physics, it is often used to quantify heat transfer.
5 Must Know Facts For Your Next Test
1 kilocalorie equals 4,184 joules, which is the SI unit of energy.
Kilocalories are often used to describe the amount of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius.
In thermodynamics, kilocalories can be converted to other units such as British Thermal Units (BTUs).
The concept of specific heat capacity involves kilocalories when calculating the amount of heat needed for temperature changes in substances.
Kilocalories are distinct from nutritional calories; however, in dietary contexts, 'calorie' typically refers to a kilocalorie.
The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.
British Thermal Unit (BTU): A unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.