How to convert kilocalories to kilojoules
One kilocalorie equals 4.184 kilojoules, so multiply the number of kilocalories by 4.184:
kJ = kcal × 4.184
kcal = kJ ÷ 4.184 (1 kJ = 0.239006 kcal)
Example: 100 kcal → 100 × 4.184 = 418.4 kJ.
Going the other way, divide by 4.184, or multiply by 0.239006; the kilojoules to kilocalories converter does it for you.
Everyday values
| Kilocalories | Kilojoules | For example |
|---|---|---|
| 100 kcal | 418.4 kJ | a small snack |
| 250 kcal | 1,046 kJ | a chocolate bar, roughly |
| 500 kcal | 2,092 kJ | a light meal |
| 2,000 kcal | 8,368 kJ | a common reference daily intake on labels |
| 2,500 kcal | 10,460 kJ | another common daily reference for men |
When you need this conversion
Food energy is labelled in kilocalories (often written "Calories" with a capital C) and, in Europe and Australia, also in kilojoules. One kcal is exactly 4.184 kJ. The reference intake on EU labels is 8,400 kJ / 2,000 kcal per day. See also the calorie calculator.
Kilocalorie to kilojoule conversion table
| kcal | kJ | kcal | kJ |
|---|---|---|---|
| 50 kcal | 209.2 kJ | 550 kcal | 2,301.2 kJ |
| 100 kcal | 418.4 kJ | 600 kcal | 2,510.4 kJ |
| 150 kcal | 627.6 kJ | 650 kcal | 2,719.6 kJ |
| 200 kcal | 836.8 kJ | 700 kcal | 2,928.8 kJ |
| 250 kcal | 1,046 kJ | 750 kcal | 3,138 kJ |
| 300 kcal | 1,255.2 kJ | 800 kcal | 3,347.2 kJ |
| 350 kcal | 1,464.4 kJ | 850 kcal | 3,556.4 kJ |
| 400 kcal | 1,673.6 kJ | 900 kcal | 3,765.6 kJ |
| 450 kcal | 1,882.8 kJ | 950 kcal | 3,974.8 kJ |
| 500 kcal | 2,092 kJ | 1,000 kcal | 4,184 kJ |
About the units
- Kilocalorie (kcal): the thermochemical kilocalorie, exactly 4,184 joules (the 'Calorie' on food labels).
- Kilojoule (kJ): 1,000 joules.
Both are units of energy. The conversion factor comes from the exact definitions above, so the calculator is exact; results are only rounded for display (up to six significant digits).
Frequently asked questions
How many kilojoules are in one kilocalorie?
One kilocalorie is 4.184 kilojoules. One kilojoule is 0.239006 kilocalories.
How do I convert kilocalories to kilojoules?
Multiply the value in kilocalories by 4.184. To go back, divide by 4.184.
What is 100 kcal in kilojoules?
100 kcal = 418.4 kJ.
What is 250 kcal in kilojoules?
250 kcal = 1,046 kJ.
Sources
- NIST Special Publication 811 (2008), Guide for the Use of the International System of Units (SI), Appendix B: conversion factors.
- NIST Handbook 44 (2024), Appendix C: General tables of units of measurement.
Last reviewed 5 October 2026. Results are estimates; see our disclaimer.