Joules to Kilojoules Converter

1 joule (J) equals 0.001 kilojoules (kJ).

Quick answer

  • 1 joule = 0.001 kilojoules
  • 1 kilojoule = 1,000 joules
  • Formula: kJ = J ÷ 1,000

1 joule = 0.001 kilojoules

How to convert joules to kilojoules

kJ = J ÷ 1,000

To convert joules to kilojoules, divide the number of joules by 1,000.

Example: 42 J to kJ

  1. Start with the value in joules: 42 J.
  2. Divide by 1,000: 42 ÷ 1,000 = 0.042.
  3. Result: 42 joules = 0.042 kilojoules.

Going the other way, 1 kilojoule = 1,000 joules, so to convert kilojoules back to joules you multiply by the same number. See kilojoules to joules.

Joules to kilojoules conversion table

Joules (J)Kilojoules (kJ)
0.1 J 0.0001 kJ
0.2 J 0.0002 kJ
0.3 J 0.0003 kJ
0.4 J 0.0004 kJ
0.5 J 0.0005 kJ
0.6 J 0.0006 kJ
0.7 J 0.0007 kJ
0.8 J 0.0008 kJ
0.9 J 0.0009 kJ
1 J 0.001 kJ
1.5 J 0.0015 kJ
2 J 0.002 kJ
2.5 J 0.0025 kJ
3 J 0.003 kJ
3.5 J 0.0035 kJ
4 J 0.004 kJ
4.5 J 0.0045 kJ
5 J 0.005 kJ
6 J 0.006 kJ
7 J 0.007 kJ
7.5 J 0.0075 kJ
8 J 0.008 kJ
9 J 0.009 kJ
10 J 0.01 kJ
11 J 0.011 kJ
12 J 0.012 kJ
13 J 0.013 kJ
14 J 0.014 kJ
15 J 0.015 kJ
16 J 0.016 kJ
17 J 0.017 kJ
18 J 0.018 kJ
19 J 0.019 kJ
20 J 0.02 kJ
21 J 0.021 kJ
22 J 0.022 kJ
23 J 0.023 kJ
24 J 0.024 kJ
25 J 0.025 kJ
26 J 0.026 kJ

More J to kJ values

What is a joule?

The joule is the SI unit of energy, work and heat.

More about joules →

What is a kilojoule?

The kilojoule is 1,000 joules. It is the unit of food energy on labels in Australia, New Zealand and the EU (alongside kcal), and a common unit in chemistry.

More about kilojoules →

Convert joules to other units

Convert other units to kilojoules

Frequently asked questions

How many kilojoules are in a joule?

One joule is 0.001 kilojoules.

How many joules are in a kilojoule?

One kilojoule is 1,000 joules.

What is the formula to convert joules to kilojoules?

kJ = J ÷ 1,000.