Why food labels differ by country
The joule is the international (SI) unit of energy, so several food systems adopted it. Australia and New Zealand print kilojoules only. The EU and UK print both kJ and kcal on every label. The US and Canada stayed with "Calories". The energy in the food is identical; only the ruler changes, which is why a muesli bar reads 800 kJ in Sydney and 191 kcal in New York.
A food Calorie is a kilocalorie
The calorie that chemists defined is tiny — the energy to warm one gram of water by one degree Celsius. Food energy is measured in thousands of them, so every "Calorie" on a label or menu is actually a kilocalorie. Apps, labels, and this site all follow that convention: calorie means kcal.
The 4.184 factor
One kilocalorie equals 4.184 kilojoules, the thermochemical definition. So the conversion runs both ways with one number: kJ ÷ 4.184 = kcal, and kcal × 4.184 = kJ. For mental math, dividing kilojoules by 4 gets within about 4%.
The reference table above includes 8,700 kJ because Australian labels use it as the average adult's daily intake benchmark — 2,079 kcal, sitting close to the 2,000-kcal convention on US labels. Both are population averages rather than personal targets. Your own maintenance number comes from your size and activity, which is what the TDEE calculator estimates, and the calorie calculator turns into eating targets.
