How to convert kilojoules to joules
To convert kilojoules to joules, multiply by 1,000. Energy conversions connect nutrition, electricity bills, heating systems and physics.
Kilojoule to Joule conversion table
| Kilojoule (kJ) | Joule (J) |
|---|---|
| 0.1 kJ | 100 J |
| 0.5 kJ | 500 J |
| 1 kJ | 1,000 J |
| 2 kJ | 2,000 J |
| 3 kJ | 3,000 J |
| 4 kJ | 4,000 J |
| 5 kJ | 5,000 J |
| 10 kJ | 10,000 J |
| 20 kJ | 20,000 J |
| 25 kJ | 25,000 J |
| 50 kJ | 50,000 J |
| 100 kJ | 100,000 J |
| 500 kJ | 500,000 J |
| 1,000 kJ | 1,000,000 J |
About the units
Kilojoule (kJ)
A kilojoule is 1,000 joules and appears on food labels in many countries.
Joule (J)
The joule is the SI unit of energy, the work done by one newton over one meter.
How to use this converter
- Type the number of kilojoules (kJ) in the input box.
- The result in joules appears instantly — no button needed.
- See the same value in every other energy unit just below.
- Use “Swap units” to convert joules back to kilojoules.
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 joules are in one kilojoule?
One kilojoule equals 1,000 joules. 1,000 is the exact factor used by this converter.
How do I convert kilojoules to joules?
Multiply the value in kilojoules by 1,000. To go the other way, multiply joules by 0.001.
What is 10 kJ in J?
10 kJ = 10,000 J. Also, 5 kJ = 5,000 J and 100 kJ = 100,000 J.
What is the difference between a kilojoule and a joule?
A kilojoule is 1,000 joules and appears on food labels in many countries. The joule is the SI unit of energy, the work done by one newton over one meter.
Is this tool free and private?
Yes — the Kilojoule to Joule 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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