How many kilojoules are in a calorie?

One food calorie (kilocalorie, kcal) equals 4.184 kilojoules. Multiply your calorie figure by 4.184 to get kilojoules.

Are these the calories shown on food labels?

Yes — nutrition labels list kilocalories (kcal), the food or large calorie, which is what this converter uses.

How do I convert kilojoules back to calories?

Divide the kilojoule value by 4.184. For example, 837 kJ ÷ 4.184 ≈ 200 kcal. Just type into the kilojoules field and the tool converts back automatically.

Which countries use kilojoules on food labels?

Australia and New Zealand label food energy primarily in kilojoules, and EU labels show both kJ and kcal. The US and UK lead with calories (kcal). This converter bridges the two.

Is a kilojoule bigger or smaller than a calorie?

A kilojoule is smaller. Since 1 kcal = 4.184 kJ, any calorie figure becomes a larger number in kilojoules — for instance a 100 kcal snack is 418.4 kJ.

Does this tool send my data anywhere?

No — all calculations run locally in your browser and nothing is uploaded.

What is the Calories to Kilojoules Converter?

Free calories to kilojoules converter: 1 kcal = 4.184 kJ. Convert food energy between calories (kcal) and kilojoules in both directions, entirely in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Calories to Kilojoules Converter

Name: Calories to Kilojoules Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Food energy is labelled as calories (kcal) in some countries and kilojoules (kJ) in others, so converting between them is a daily need for anyone reading international nutrition labels. The conversion is exact: 1 kcal = 4.184 kJ. This tool converts in both directions — type into either field and the other updates instantly.

The label confusion explained

The word “calorie” is used inconsistently. In everyday language and on most food labels, “calorie” means kilocalorie (kcal) — the amount of energy needed to raise 1 kg of water by 1 °C. This is the large calorie, sometimes written with a capital C (Calorie). Physicists use a “small calorie” (lowercase c) equal to 1/1000th of a kcal, which never appears on food packaging. When this tool says calories, it always means kcal.

Where each unit appears on labels:

Australia and New Zealand: lead with kJ, also show kcal
European Union: show both kJ and kcal, kJ first
United Kingdom: show both; front-of-pack often shows kcal only
United States and Canada: show kcal only, labelled simply as “Calories”

This is the main reason people need this converter — an Australian nutrition label listing 1,800 kJ per 100 g looks very different from a US label showing 430 kcal, but they describe the same energy level.

How it works

Both units measure the same thing — food energy — so a single exact factor connects them. To convert calories to kilojoules the tool computes kJ = kcal × 4.184; to reverse it, kcal = kJ ÷ 4.184. The kilocalorie here is the food (large) calorie shown on labels, equal to 1,000 small calories. Because the factor is a definition, results are exact rather than rounded approximations.

Reference table

Calories (kcal)	Kilojoules (kJ)	Everyday reference
50	209.2	Small apple
100	418.4	Slice of bread
200	836.8	Medium banana
500	2,092	Large fast-food burger
2,000	8,368	Typical adult daily intake
2,500	10,460	Higher-energy adult daily intake

Worked example

An Australian cereal label reads 1,526 kJ per serving. To compare with a US product listed in kcal:

1,526 ÷ 4.184 = 364.7 kcal

Going the other direction: a US snack bar at 200 kcal equals 200 × 4.184 = 836.8 kJ.

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