Convert Joule to Kilojoule
Use this free converter to change joules (J) into kilojoules (kJ). Joule and kilojoule both measure energy. As a quick reference, 1 J equals 0.001 kJ, and 1 kJ equals 1000 J.
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Kilojoule (kJ)
0.001
1 J = 0.001 kJ
Energy conversion table
| Joule | Kilojoule |
|---|---|
| 0.01 | 0.00001 |
| 0.1 | 0.0001 |
| 0.5 | 0.0005 |
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 5 | 0.005 |
| 10 | 0.01 |
| 20 | 0.02 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
| 1,000 | 1 |
How to convert Joule to Kilojoule
Multiply the joule value by 0.001 to get kilojoules.
- Enter the number of joules you want to convert.
- The converter instantly shows the equivalent value in kilojoules.
- Worked example: 15 J × 0.001 = 0.015 kJ.
- Use the swap button to reverse the conversion (kilojoule to joule).
About these units
Joule (J)
- Definition
- The joule (J) is the SI unit of energy, the work done by a force of one newton over one meter.
- History
- Named after physicist James Prescott Joule, who studied the link between heat and work.
- Current use
- Joules measure energy, work, and heat throughout science and engineering.
Kilojoule (kJ)
- Definition
- A kilojoule (kJ) is 1,000 joules, a practical size for food energy and mechanical work.
- History
- It is a metric multiple of the joule.
- Current use
- Kilojoules express food energy on nutrition labels in many countries.
Frequently asked questions
How many kilojoules are in a joule?
There are 0.001 kJ in 1 J. To convert, multiply the number of joules by 0.001.
How do I convert joules to kilojoules?
Multiply the joule value by 0.001 to get kilojoules. For example, 10 J = 0.01 kJ.
Is this joule-to-kilojoule converter free?
Yes. This converter is completely free, runs entirely in your browser, and requires no sign-up. Your inputs never leave your device.
Convert Joule to other energy units
| Unit | 1 Joule equals |
|---|---|
| Kilojoule (kJ) | 0.001 kJ |
| Calorie (cal) | 0.23900574 cal |
| Kilocalorie (kcal) | 0.00023900574 kcal |
| Watt Hour (Wh) | 0.00027777778 Wh |
| Kilowatt Hour (kWh) | 2.7778e-7 kWh |
| Electronvolt (eV) | 6.2415e+18 eV |
| British Thermal Unit (BTU) | 0.00094781712 BTU |
| Foot-Pound (ft·lb) | 0.73756215 ft·lb |