Joules to kilojoules
Type a value in joules to see it in kilojoules straight away, or type in the second box to convert back.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the joules box.
- Read the result in kilojoules as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
kJ = J × 0.001
Multiply the value in joules by 0.001 to get kilojoules.
Example
To convert 25 J to kilojoules: 25 × 0.001 = 0.025 kJ.
Conversion table
| Joules (J) | Kilojoules (kJ) |
|---|---|
| 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 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1,000 | 1 |
About the units
- Joule
- The SI unit of energy, equal to the work done by a force of one newton moving an object one meter.
- Kilojoule
- Exactly 1000 joules. It appears on food labels next to the calorie figure.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many kilojoules are in one joule?
1 J = 0.001 kJ exactly.
How do I convert joules to kilojoules?
Use kJ = J × 0.001. For example, 25 J = 0.025 kJ.
How many joules are in one kilojoule?
1 kJ = 1,000 J.
Which calorie do these converters use?
The thermochemical calorie, exactly 4.184 joules, the factor many countries use to turn kcal into kJ on food labels. The International Table calorie is 4.1868 joules, less than 0.07% larger.
What is the difference between kW and kWh?
A kilowatt is a unit of power, the rate of using energy, while a kilowatt-hour is an amount of energy. A 2 kW heater running for three hours uses 6 kWh.