J to KJ Converter
Type a value in joules to see it in kilojoules as you type, with the exact formula and a reference chart.
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How this was calculated
- 1 kilojoule = 1,000 joules
- 4,184 ÷ 1,000 = 4.184 kJ
| J | kJ |
|---|---|
| 1 J | 0.001 kJ |
| 10 J | 0.01 kJ |
| 50 J | 0.05 kJ |
| 100 J | 0.1 kJ |
| 250 J | 0.25 kJ |
| 500 J | 0.5 kJ |
| 1,000 J | 1 kJ |
| 2,500 J | 2.5 kJ |
| 4,184 J | 4.184 kJ |
| 5,000 J | 5 kJ |
| 10,000 J | 10 kJ |
| 50,000 J | 50 kJ |
| 100,000 J | 100 kJ |
| kJ | J |
|---|---|
| 0.001 kJ | 1 J |
| 0.01 kJ | 10 J |
| 0.1 kJ | 100 J |
| 0.5 kJ | 500 J |
| 1 kJ | 1,000 J |
| 2 kJ | 2,000 J |
| 5 kJ | 5,000 J |
| 10 kJ | 10,000 J |
| 50 kJ | 50,000 J |
| 100 kJ | 100,000 J |
| 500 kJ | 500,000 J |
| 1,000 kJ | 1,000,000 J |
How to convert joules to kilojoules
1 joule = 0.001 kilojoules. To convert joules to kilojoules, divide by 1,000 (or multiply by 0.001). The joule is the SI unit of energy, one newton-meter. A kilojoule is 1,000 joules; food labels in Australia, New Zealand and the EU list energy in kJ.
Worked examples
- 500 joules = 0.5 kJ (500 ÷ 1,000)
- 4,184 joules = 4.184 kJ (4,184 ÷ 1,000)
- 25,000 joules = 25 kJ (25,000 ÷ 1,000)
Where this conversion comes up
Joules are used for physics and electrical energy; kilojoules for food labels outside the US and exercise machines. Joules get large quickly, so heat, work and food-energy figures are converted to kilojoules by dividing by 1,000. A 4,184 J heat input (one food Calorie) is 4.184 kJ.
Quick estimate
Move the decimal point three places left: 2,500 J = 2.5 kJ.
Common mistakes
- Multiplying instead of dividing. A kilojoule is larger than a joule, so the number of kilojoules must come out smaller: 500 joules = 0.5 kJ.
Going the other way? Use the kj to j converter. Related energy converters: kj to calories, kcal to kj, kj to kcal, kwh to mwh.
Frequently asked questions
How do you convert joules to kilojoules?
Multiply the joules by 0.001 (or divide by 1,000). For example, 4,184 joules is 4.184 kilojoules.
How many kilojoules are in one joule?
One joule is 0.001 kilojoules. The joule is the SI unit of energy, one newton-meter.
What is 25,000 joules in kilojoules?
25,000 joules is 25 kilojoules.
Is there a quick way to estimate joules to kilojoules?
Move the decimal point three places left: 2,500 J = 2.5 kJ.