Energy converter
A kilowatt-hour measures energy, not power. Calories here are thermochemical; a food Calorie is one kilocalorie.
Edit either value. Use a decimal point; commas group thousands. Rounding affects display only.
How to convert joules to kilojoules
Choose any of the 7 supported units. All conversions within this category share the same calculation engine.
Formula coefficients shown rounded. Calculations use the stored factors before display rounding.
A worked example
For 10 J, the result is approximately 0.01 kJ. To go the other way, edit the result above or swap the units.
A kilowatt-hour measures energy, not power. Calories here are thermochemical; a food Calorie is one kilocalorie.
Where the numbers come from
Factors follow NIST conversion references and documented unit definitions. Read our accuracy and rounding notes.
The table and method describe this page’s original pair. Changing units above does not change this reference section.
| Joules (J) | Kilojoules (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 |
| 500 | 0.5 |
| 1000 | 1 |