📏 Joules to Kilojoules Converter
Convert joules (J) to kilojoules (kJ) instantly, with the formula, a worked example and a conversion table.
Quick answer: 1 joule (J) = 0.001 kilojoules (kJ). Formula: kJ = J × 0.001.
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Joules to Kilojoules Converter inputs
Result
Joules to Kilojoules conversion table
| Joules (J) | Kilojoules (kJ) |
|---|---|
| 0.1 J | 0.0001 kJ |
| 0.5 J | 0.0005 kJ |
| 1 J | 0.001 kJ |
| 2 J | 0.002 kJ |
| 3 J | 0.003 kJ |
| 5 J | 0.005 kJ |
| 10 J | 0.01 kJ |
| 20 J | 0.02 kJ |
| 25 J | 0.025 kJ |
| 50 J | 0.05 kJ |
| 100 J | 0.1 kJ |
| 1,000 J | 1 kJ |
Other energy conversions
How to convert joules to kilojoules
Multiply the number of joules by 0.001 to get kilojoules: kJ = J × 0.001.
Example: 5 J = 0.005 kJ.
The joule (J) and the kilojoule (kJ) are both units of energy. Need the opposite direction? Use the kJ to J converter.
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Metric and imperial units
The metric system (SI) is used by almost every country and by science worldwide. Its units scale by powers of ten – 1 kilometer is 1,000 meters, 1 meter is 100 centimeters – which makes conversions inside the system easy. The imperial and US customary systems (inches, feet, pounds, gallons) are still used daily in the United States and partly in the UK.
Since 1959 the inch has been defined as exactly 2.54 centimeters and the pound as exactly 0.45359237 kilograms, so conversions between the two systems are exact. Note that a US gallon (3.785 L) and an imperial gallon (4.546 L) are different – choose the right one above.
This converter covers 10 categories and 66 units: length, weight, temperature, volume, area, speed, time, data, energy, pressure.
Frequently asked questions
How many kilojoules are in a joule?
1 joule = 0.001 kilojoules.
How do I convert joules to kilojoules?
Use the formula kJ = J × 0.001. For example, 5 J = 0.005 kJ.
How do I convert kilojoules back to joules?
1 kilojoule = 1,000 joules. Use the kJ to J converter linked on this page.
Are these conversions exact?
Yes – all factors use the internationally defined values (for example 1 inch = 2.54 cm exactly, 1 pound = 0.45359237 kg exactly). Results are rounded to 8 significant digits for display.