Convert Joules to Kilojoules
One joule equals 0.001 kilojoules. Type any value to convert joules to kilojoules instantly — with a full reference table below.
Convert Joules to Kilojoules
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How to convert Joules to Kilojoules
To convert joules to kilojoules, multiply by 0.001. One joule equals 0.001 kJ, and one kilojoule equals 1,000 J.
- Take the value in joules — for example 7.5 J.
- Multiply by 0.001 (the number of kilojoules in one joule).
- 7.5 × 0.001 = 0.0075 kJ.
Shortcut: the factor is a power of ten, so just move the decimal point 3 places to the left.
Joules to Kilojoules conversion table
| Joules | Kilojoules |
|---|---|
| 1 J | 0.001 kJ |
| 2 J | 0.002 kJ |
| 5 J | 0.005 kJ |
| 10 J | 0.01 kJ |
| 20 J | 0.02 kJ |
| 50 J | 0.05 kJ |
| 100 J | 0.1 kJ |
| 200 J | 0.2 kJ |
| 500 J | 0.5 kJ |
| 1,000 J | 1 kJ |
| 2,000 J | 2 kJ |
| Kilojoules | Joules |
|---|---|
| 1 kJ | 1,000 J |
| 2 kJ | 2,000 J |
| 5 kJ | 5,000 J |
| 10 kJ | 10,000 J |
| 20 kJ | 20,000 J |
| 50 kJ | 50,000 J |
| 100 kJ | 100,000 J |
| 200 kJ | 200,000 J |
| 500 kJ | 500,000 J |
| 1,000 kJ | 1,000,000 J |
| 2,000 kJ | 2,000,000 J |
About converting Joules to Kilojoules
Joules (J) and Kilojoules (kJ) are both units of energy. The exact factor is 1 J = 0.001 kJ, so multiply by 0.001 to go from joules to kilojoules (or divide to go back).
The conversion runs entirely in your browser. Need the reverse? Use the Kilojoules to Joules converter, or the full unit converter for every unit at once.
Real-world energy in joules and kilojoules
| Example | Joules | Kilojoules |
|---|---|---|
| One food Calorie (kcal) | 4,184 J | 4.184 kJ |
| A 100 W bulb running for one hour | 360,000 J | 360 kJ |
| A smartphone battery (≈19 Wh) | ≈ 69,300 J | ≈ 69.3 kJ |
“≈” marks typical values; the rest are defined or measured figures.
The units
The SI unit of energy: the work done by one newton over one metre.
Used for: Science and food labels (kJ).
1,000 joules.
Used for: Food energy on labels in Australia and the EU.
The thermochemical calorie is exactly 4.184 J and a kilowatt-hour is exactly 3.6 MJ, so these factors are exact.