Kilojoules to Kilocalories Converter (kJ to kcal)

Australian and New Zealand nutrition panels give energy in kilojoules, often with no kcal figure at all, and EU packs list kJ first. Anyone used to counting Calories, or following a plan written in kcal, needs to divide by 4.184 to read those labels. The percentage daily intake on Australian packs is worked out against an average adult diet of 8,700 kJ, a little over 2,000 kcal.

Cyclists meet kilojoules too: power meters total the work done at the pedals in kJ. Because the body turns food energy into pedaling work at roughly 20 to 25% efficiency, the kJ figure for a ride is often used as a rough stand-in for the kcal burned. This page converts the energy itself and applies no efficiency factor.

How to use this tool

1. Type a value in the Kilojoule box to see it in kilocalories, or type in the Kilocalorie box to convert the other way.
2. Press ⇄ to swap the two units, or Load example for a typical value.
3. Check the charts below for common values; for other units, open the Energy converter.

Formula

kcal = kJ ÷ 4.184

kJ = kcal × 4.184

Both factors come from exact definitions: 1 kilocalorie = 4.184 kilojoules and 1 kilojoule = 0.239005736138 kilocalories (shown to 12 significant digits).

Example

Two conversions worked with the same factors the converter uses:

8700 kJ × 0.239005736138 ≈ 2079.35 kcal

450 kcal × 4.184 = 1882.8 kJ

Kilojoule to Kilocalorie chart

Common values from kilojoules to kilocalories, rounded to four decimal places.

Kilocalorie to Kilojoule chart

The reverse direction for values people often look up.

Energy figures given in kilojoules

Quick mental estimate

Divide by 4, then take away 4% of the answer: 8,700 kJ → 2,175 − 87 = 2,088 kcal. That matches dividing by about 4.17, so the estimate runs about 0.4% high.

Use the converter or the charts when the exact figure matters.

The two units

Kilojoule (kJ): A kilojoule (kJ) is 1,000 joules. Food labels in many countries list energy in kJ alongside kilocalories, with 1 kcal equal to 4.184 kJ.

Kilocalorie (kcal): A kilocalorie (kcal) is 1,000 calories, exactly 4,184 J in the thermochemical definition used here. It is the "Calorie" printed on food and drink labels.