The kilojoule (kJ) equals 1,000 joules and is the standard unit for expressing food energy content and chemical reaction energies in countries using the metric system. Food labels in Australia, Europe, and many other regions display energy values in kilojoules alongside or instead of calories. One kilojoule equals approximately 238.8 calories or about 0.239 kilocalories.

The kilocalorie (kcal), commonly called the 'Calorie' on food labels, equals 1,000 calories or 4,184 joules, the standard unit for measuring dietary energy worldwide. When nutrition facts list '200 Calories,' they mean 200 kilocalories, representing the energy your body can extract from that food. One kilocalorie equals exactly 4.184 kilojoules, the figure used on food packaging in many countries.