Direct conversion
Convert joule [J] to kilojoule [kJ] instantly with formula, examples, chart, and FAQs.
Quick answer
Use the calculator below for any custom value, then check the formula, examples, chart, and reverse conversion links.
1 joule [J] = 0.001 kilojoule [kJ]
1 joule [J] = 0.001 kilojoule [kJ]
Example: 1 joule [J] equals 0.001 kilojoule [kJ].
Energy conversions use joule as the reference unit, including electrical, thermal, nutrition, and mechanical energy units.
Displayed results are rounded for readability. The calculator keeps enough precision for everyday use and switches to scientific notation for very large or very small values. Last reviewed: 2026-05-21.
The joule is the SI derived unit of energy, work, and heat.
HistoryThe joule is named after James Prescott Joule and became the standard SI energy unit.
Current useJoules are used in physics, engineering, nutrition science, batteries, heating, and mechanical work.
The kilojoule is an energy unit equal to 1000 joules.
HistoryKilojoules are a metric multiple of joules and became common where joules are too small.
Current useKilojoules are used for food energy labels, thermodynamics, exercise energy, and engineering calculations.
| joule [J] | kilojoule [kJ] |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 5 | 0.005 |
| 10 | 0.01 |
| 20 | 0.02 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
| 1000 | 1 |
Use this formula: 1 joule [J] = 0.001 kilojoule [kJ] Enter your value in the calculator and the result updates instantly.
1 joule [J] equals 0.001 kilojoule [kJ].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.