kcal to kJ Converter
Convert kilocalorie (food calorie) to kilojoule instantly. 1 kcal = 4.184 kJ, worked steps and a full reference table.
How to use it
- Type the value in kilocalorie (food calorie) — the result updates as you type.
- Use Swap to flip the direction, or change either dropdown to convert between any two units.
- Click the result to copy it. The URL updates too, so you can bookmark or share the exact conversion.
Examples
| 1 kcal | 4.184 kJ |
| 5 kcal | 20.92 kJ |
| 10 kcal | 41.84 kJ |
| 100 kcal | 418.4 kJ |
One kilocalorie (food calorie) equals 4.184 kilojoules (kJ). To convert kilocalorie (food calorie)s to kilojoules, multiply by 4.184; to go back the other way, multiply by 0.23900574 instead.
The converter above does it as you type and shows the working underneath, so you can check the arithmetic rather than take the number on trust.
What kilocalorie (food calorie)s and kilojoules actually measure
Kilocalorie (food Calorie) (kcal) — A kilocalorie is a thousand small calories. Food labels call it a Calorie, capitalised. Nutrition and diet planning.
Kilojoule (kJ) — A kilojoule is a thousand joules. Nutrition labels outside the US, and heating calculations.
kcal to kJ conversion table
The most common values, worked out in advance. Anything not listed can be typed straight into the converter.
| kcal | kJ |
|---|---|
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 5 kcal | 20.92 kJ |
| 10 kcal | 41.84 kJ |
| 25 kcal | 104.6 kJ |
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
How to convert kilocalorie (food calorie)s to kilojoules by hand
Multiply the number of kilocalorie (food calorie)s by 4.184.
For example, 25 kcal × 4.184 = 104.6 kJ.
Going the other way, divide by 4.184 — or multiply by 0.23900574, which is the same thing and easier to do in your head.
Everything runs in your browser
There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.
Questions people ask
How many kJ are in 1 kcal?
1 kcal equals exactly 4.184 kJ. Multiply any value in kilocalorie (food calorie) by 4.184 to get kilojoule.
Is anything uploaded to a server?
No. The whole calculation happens in your browser. Nothing is sent anywhere, and the page keeps working offline once loaded.
Last updated 18 August 2026