There are 4.186 joules in one calorie. The calorie is a unit of energy in the International System of Units. It is a measurement of the amount of heat needed to raise one gram of water by 1 degree Celsius from a standard initial temperature at atmospheric pressure. It is often abbreviated as cal or kcal. The calorie is not the same as a joule (the SI derived unit of energy), although many people use the two interchangeably. The calorie is also known as the small calorie or food calorie, but it should not be confused with the large calorie based on heating a kilogram of water.
The calorie is the unit of energy used in nutrition and dietetics. It is commonly expressed in kilocalories and is the most common unit of energy in food labels. Although it was recommended more than 30 years ago that joules be used instead of calories, values for food energy in the Codex Alimentarius continue to be given in both units, with kilocalories appearing first and joules following within parenthesis or in a smaller font.
If you are trying to understand a nutritional label or calculate the energy content of a particular food, it is important to know how many joules are in a calorie. You can convert calorie to joule using the calculator below. Simply enter the number of calories you want to convert and click Calculate. The converter will automatically display the corresponding number of joules.