Megajoules to Kilojoules
An instant megajoules-to-kilojoules converter, with the formula and a reference table below.
| Megajoules | Kilojoules |
|---|---|
| 1 MJ | 1000 kJ |
| 2 MJ | 2000 kJ |
| 3 MJ | 3000 kJ |
| 5 MJ | 5000 kJ |
| 10 MJ | 10000 kJ |
| 25 MJ | 25000 kJ |
| 50 MJ | 50000 kJ |
| 100 MJ | 100000 kJ |
How to use
- Enter a value in the Megajoules field.
- The Kilojoules figure appears immediately — no button to press.
- Typing in the Kilojoules field converts back to Megajoules the same way.
- Use the reference table for the values that come up most often.
Megajoules to Kilojoules formula
Converting megajoules to kilojoules is a single multiplication by 1000.
kJ = MJ × 1000
Put another way, one megajoule is exactly 1,000 kilojoules.
Why this factor: the megajoule and the kilojoule are both defined against the joule, so dividing one definition by the other gives 1000 directly. Both definitions are set out in full below.
To go the other way, divide by 1000 — or use the Kilojoules to Megajoules converter, which is the same calculation reversed.
Worked example
Start with 2000 MJ. Multiply by 1000 to get 2000000 kJ.
2000 MJ × 1000 = 2000000 kJ
The converter above does this for any value you type, in either direction.
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.
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.
Megajoules vs Kilojoules
The megajoule and the kilojoule 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 kilojoules are in a megajoule?
One megajoule equals 1000 kilojoules.
What is the formula to convert megajoules to kilojoules?
Multiply the number of megajoules by 1000. To reverse it, divide by 1000 instead.
How do I convert kilojoules back to megajoules?
Divide by 1000, which is the same as multiplying by 0.001.
How many kilojoules are in 10 megajoules?
10 MJ works out to 10000 kJ.
How is the megajoule defined?
Exactly 1×10⁶ joules. One kilowatt-hour is exactly 3.6 MJ.