kJ vs calories
Kilojoules (kJ) and calories (kcal) measure the same thing in different units. One calorie is 4.184 kJ, so 2,000 kcal is 8,368 kJ. Australian food labels show kJ, and many other countries show calories.
Updated 21 October 2026. Sources named on the page.
- What each unit is
- The exact factor and a quick mental rule
- A table of common amounts
- Why Australia uses kilojoules
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Common amounts
Kilojoules = kilocalories x 4.184. Kilocalories = kilojoules / 4.184.
Everyday amounts
| Item | kJ | kcal |
|---|---|---|
| A small snack | 600 kJ | 143 kcal |
| A light meal | 1,500 kJ | 359 kcal |
| The Australian label average day | 8,700 kJ | 2,079 kcal |
| A 2,000 kcal day | 8,368 kJ | 2,000 kcal |
Sources: The thermochemical calorie is defined as 4.184 joules, so 1 kcal = 4.184 kJ; Australian food labels use an average adult daily intake of 8,700 kJ as a reference
Figures and sources checked 21 October 2026. General information, not medical advice.
Are calories and Calories the same?
On food labels, the calorie people mean is a kilocalorie (kcal), sometimes written Calorie with a capital C. They are the same thing.
A quick mental rule
Divide kilojoules by 4 for a rough number of calories. 1,000 kJ is about 250 calories by this rule, and 239 by the exact one. For a label you are reading in a shop, the rule is close enough.
Why Australia uses kilojoules
Australia and New Zealand label food in kilojoules, the metric unit of energy. Many other countries use kilocalories, which is why recipes and apps from overseas can look different.
Which should I use?
Use the one on the label in front of you, and convert when you compare. The calculators on this site show both.
Questions
How many kJ are in a calorie?
One kilocalorie is 4.184 kilojoules.
How many calories are in 1,000 kJ?
About 239 kcal.
Is 8,700 kJ a target?
No. It is the average adult daily intake used on labels so foods can be compared. Your own needs differ.
Why do apps show different numbers?
Some use calories and some use kilojoules, and food databases can differ. Convert with 4.184 to compare.
Keep going
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