Food Calorie to Joule Converter

About this calculator

The “Calorie” printed on food labels (capital C, formally a kilocalorie or kcal) is a unit of energy from an older thermochemical system, while the joule is the SI unit of energy used throughout physics, chemistry and most of the world outside US food labeling. The conversion is fixed and exact by definition: 1 kcal = 4184 J (based on the thermochemical calorie of exactly 4.184 J, scaled up a thousand times).

Nutrition scientists, exercise physiologists and anyone reading food energy content in a country that labels in kilojoules — most food labels outside the US show both kcal and kJ — rely on this conversion to reconcile the two systems, since a food energy value is meaningless without knowing which unit it’s expressed in. Enter an energy value and pick a direction to convert between food Calories and joules.