How to convert kilocalories to kilojoules
To convert kilocalories to kilojoules, multiply by 4.184. Energy conversions connect nutrition, electricity bills, heating systems and physics.
Kilocalorie to Kilojoule conversion table
| Kilocalorie (kcal) | Kilojoule (kJ) |
|---|---|
| 0.1 kcal | 0.4184 kJ |
| 0.5 kcal | 2.092 kJ |
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 3 kcal | 12.552 kJ |
| 4 kcal | 16.736 kJ |
| 5 kcal | 20.92 kJ |
| 10 kcal | 41.84 kJ |
| 20 kcal | 83.68 kJ |
| 25 kcal | 104.6 kJ |
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
About the units
Kilocalorie (kcal)
A kilocalorie (food Calorie) equals 1,000 small calories, or 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 kilocalories (kcal) 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 kilocalories.
When you’ll use the kilocalorie to kilojoule conversion
Converting kilocalories to kilojoules comes up more often than you might expect — for example when understanding your electricity bill in kWh, reading appliance labels, or comparing food energy in kcal and kJ. Type your number once and you get the exact answer plus every related unit, so you don’t need to convert twice.
💡 For a quick estimate in your head, multiply by about 4.2 (the exact factor is 4.184).
Watch out for these mix-ups
- Food “Calories” are kilocalories (kcal), not small calories.
- kW is power (a rate); kWh is energy (an amount).
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 kilocalorie?
One kilocalorie equals 4.184 kilojoules. 4.184 is the exact factor used by this converter.
How do I convert kilocalories to kilojoules?
Multiply the value in kilocalories by 4.184. To go the other way, multiply kilojoules by 0.239005736138.
What is 10 kcal in kJ?
10 kcal = 41.84 kJ. Also, 5 kcal = 20.92 kJ and 100 kcal = 418.4 kJ.
What is the difference between a kilocalorie and a kilojoule?
A kilocalorie (food Calorie) equals 1,000 small calories, or 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 Kilocalorie 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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