Kilojoules to Megajoules
An instant kilojoules-to-megajoules converter, with the formula and a reference table below.
| Kilojoules | Megajoules |
|---|---|
| 1 kJ | 0.001 MJ |
| 2 kJ | 0.002 MJ |
| 3 kJ | 0.003 MJ |
| 5 kJ | 0.005 MJ |
| 10 kJ | 0.01 MJ |
| 25 kJ | 0.025 MJ |
| 50 kJ | 0.05 MJ |
| 100 kJ | 0.1 MJ |
How to use
- Enter a value in the Kilojoules field.
- The Megajoules figure appears immediately — no button to press.
- Typing in the Megajoules field converts back to Kilojoules the same way.
- Use the reference table for the values that come up most often.
Kilojoules to Megajoules formula
The factor from kilojoules to megajoules is 0.001.
MJ = kJ × 0.001
Put another way, one kilojoule is exactly 1/1,000 of a megajoule.
Why this factor: the kilojoule and the megajoule are both defined against the joule, so dividing one definition by the other gives 0.001 directly. Both definitions are set out in full below.
To go the other way, divide by 0.001 — or use the Megajoules to Kilojoules converter, which is the same calculation reversed.
Worked example
Given 100 kJ, multiplying by 0.001 yields 0.1 MJ.
100 kJ × 0.001 = 0.1 MJ
The converter above does this for any value you type, in either direction.
What is a kilojoule?
A kilojoule is 1,000 joules, the metric unit of food energy.
Definition: Exactly 1,000 joules.
Where it is used: Nutrition labels in Europe and Australia, and heating and cooling loads.
What is a megajoule?
A megajoule is one million joules, used for substantial energy quantities.
Definition: Exactly 1×10⁶ joules. One kilowatt-hour is exactly 3.6 MJ.
Where it is used: Fuel energy content, natural gas billing, and industrial energy accounting.
Kilojoules vs Megajoules
The kilojoule and the megajoule belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many megajoules are in a kilojoule?
One kilojoule equals 0.001 megajoules.
What is the formula to convert kilojoules to megajoules?
Multiply the number of kilojoules by 0.001. To reverse it, divide by 0.001 instead.
How do I convert megajoules back to kilojoules?
Divide by 0.001, which is the same as multiplying by 1000.
How many megajoules are in 10 kilojoules?
10 kJ works out to 0.01 MJ.
How is the kilojoule defined?
Exactly 1,000 joules.