Megajoules to Joules
Convert megajoules to joules instantly — one megajoule is 1e+06 joules.
| Megajoules | Joules |
|---|---|
| 1 MJ | 1000000 J |
| 2 MJ | 2000000 J |
| 3 MJ | 3000000 J |
| 5 MJ | 5000000 J |
| 10 MJ | 10000000 J |
| 25 MJ | 25000000 J |
| 50 MJ | 50000000 J |
| 100 MJ | 100000000 J |
How to use
- Enter a value in the Megajoules field.
- The Joules figure appears immediately — no button to press.
- Typing in the Joules field converts back to Megajoules the same way.
- Use the reference table for the values that come up most often.
Megajoules to Joules formula
To convert megajoules to joules, multiply by 1000000.
J = MJ × 1000000
Why this factor: the megajoule and the joule are both defined against the joule, so dividing one definition by the other gives 1000000 directly. Both definitions are set out in full below.
To go the other way, divide by 1000000 — or use the Joules to Megajoules converter, which is the same calculation reversed.
Worked example
Start with 2000 MJ. Multiply by 1000000 to get 2000000000 J.
2000 MJ × 1000000 = 2000000000 J
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 joule?
The joule is the SI unit of energy — the work done by one newton acting over one meter.
Definition: Defined as 1 N·m, equivalently one watt-second. Named after James Prescott Joule.
Where it is used: All scientific energy calculations, food energy on European labels, and mechanical work.
Megajoules vs Joules
The megajoule is a metric unit while the joule is an SI unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many joules are in a megajoule?
One megajoule equals 1000000 joules.
What is the formula to convert megajoules to joules?
Multiply the number of megajoules by 1000000. To reverse it, divide by 1000000 instead.
How do I convert joules back to megajoules?
Divide by 1000000, which is the same as multiplying by 1e-06.
How many joules are in 10 megajoules?
10 MJ works out to 10000000 J.
How is the megajoule defined?
Exactly 1×10⁶ joules. One kilowatt-hour is exactly 3.6 MJ.