How to convert calories to kilojoules
To convert calories to kilojoules, multiply by 0.004184. Energy conversions connect nutrition, electricity bills, heating systems and physics.
Calorie to Kilojoule conversion table
| Calorie (cal) | Kilojoule (kJ) |
|---|---|
| 0.1 cal | 0.0004184 kJ |
| 0.5 cal | 0.002092 kJ |
| 1 cal | 0.004184 kJ |
| 2 cal | 0.008368 kJ |
| 3 cal | 0.012552 kJ |
| 4 cal | 0.016736 kJ |
| 5 cal | 0.02092 kJ |
| 10 cal | 0.04184 kJ |
| 20 cal | 0.08368 kJ |
| 25 cal | 0.1046 kJ |
| 50 cal | 0.2092 kJ |
| 100 cal | 0.4184 kJ |
| 500 cal | 2.092 kJ |
| 1,000 cal | 4.184 kJ |
About the units
Calorie (cal)
A (small) thermochemical calorie is exactly 4.184 joules.
Kilojoule (kJ)
A kilojoule is 1,000 joules and appears on food labels in many countries.
How to use this converter
- Type the number of calories (cal) in the input box.
- The result in kilojoules appears instantly — no button needed.
- See the same value in every other energy unit just below.
- Use “Swap units” to convert kilojoules back to calories.
Tips for better results
- Double-check which system a unit belongs to (for example US vs UK gallons).
- Use the swap button to convert in the opposite direction instantly.
- Bookmark the conversions you use most — each pair has its own page.
Frequently asked questions
How many kilojoules are in one calorie?
One calorie equals 0.004184 kilojoules. 0.004184 is the exact factor used by this converter.
How do I convert calories to kilojoules?
Multiply the value in calories by 0.004184. To go the other way, multiply kilojoules by 239.005736138.
What is 10 cal in kJ?
10 cal = 0.04184 kJ. Also, 5 cal = 0.02092 kJ and 100 cal = 0.4184 kJ.
What is the difference between a calorie and a kilojoule?
A (small) thermochemical calorie is exactly 4.184 joules. A kilojoule is 1,000 joules and appears on food labels in many countries.
Is this tool free and private?
Yes — the Calorie to Kilojoule is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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