Calories (mean) to Calories (nutritional)

Calories (mean)

A mean calorie is a unit of energy that was historically used to quantify the amount of energy required to raise the temperature of one gram of water by one degree Celsius, approximately equal to 4.184 joules.

Calories (nutritional)

A nutritional calorie, specifically a kilocalorie (kcal), is the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius. In nutritional contexts, the term "calorie" typically refers to a kilocalorie.