Calorie
A unit of heat energy. In nutrition, 1 Calorie (kcal) = 4,184 joules.
Definition
The calorie (cal) is defined as the energy needed to raise 1 gram of water by 1 °C. The nutritional Calorie (written with a capital C) is actually a kilocalorie (kcal) — the energy to raise 1 kg of water by 1 °C. Food labels always use kcal, even when written as "Calories".
Formula
1 kcal = 4,184 J = 3.968 BTU
Examples
- A medium apple contains about 95 kcal.
- Running 1 km burns roughly 60–80 kcal depending on body weight.