Calorie

The unit of heat energy in the centimeter-gram-second system of measurements. A large calorie (Calorie) is the amount of heat energy needed to raise the temperature of one kilogram of water one degree Celsius. A small calorie (calorie) is the amount of heat energy needed to raise the temperature of one gram of pure water from 14.5 to 15.5°C. One calorie is equal to 4.19 joules of energy.