Calories to KJ Converter
Convert calories to kilojoules
Frequently Asked Questions
How do I convert calories to kilojoules?
Multiply calories by 4.184. 1 calorie (kcal) = 4.184 kJ. A 2,000 calorie diet = 8,368 kJ. The converter handles both directions and shows the exact conversion factor used.
Why do some countries use kilojoules instead of calories?
Australia, New Zealand, and many European countries use kilojoules on food labels as the primary energy unit. The US, UK, and Canada primarily use calories. Both measure the same thing — food energy content.
What is the difference between calories and kilocalories?
In nutrition, "calorie" (capital C or kcal) = 1,000 small calories. A food label showing 200 Calories means 200 kcal = 200,000 small calories = 836.8 kJ. The converter uses nutritional calories (kcal) by default.
How many kilojoules should I eat per day?
Average daily needs: 8,700 kJ (2,080 kcal) for adult women, 10,500 kJ (2,510 kcal) for adult men. These vary with age, weight, height, and activity level. The converter helps translate between dietary guidelines in different units.
How do I read food labels with both units?
Most international food labels show both: "Energy: 250 kcal / 1,046 kJ". The kJ value is always about 4.2× the kcal value. If only one unit is shown, use the converter to find the other for comparison.