Joules to Megajoules
Convert joules to megajoules instantly. 1 J = 1e-06 MJ. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert joules to megajoules
To convert joules to megajoules, divide by 1,000,000 (multiply by 1e-06). The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
MJ = J × 1e-06
Joules to Megajoules conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Joules | Megajoules |
|---|---|
| 1 J | 1e-06 MJ |
| 2 J | 2e-06 MJ |
| 3 J | 3e-06 MJ |
| 5 J | 5e-06 MJ |
| 10 J | 1e-05 MJ |
| 20 J | 2e-05 MJ |
| 25 J | 2.5e-05 MJ |
| 50 J | 5e-05 MJ |
| 100 J | 0.0001 MJ |
| 500 J | 0.0005 MJ |
| 1,000 J | 0.001 MJ |
What is a joule?
The SI unit of energy: one newton-metre, or one watt for one second.
What is a megajoule?
A million joules, used for fuel energy content and gas billing.
The formula
MJ = J × 1e-06
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Joules to Megajoules
- Type the number of joules you want to convert.
- Read the result in megajoules straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked megajoules to joules page.
Joules to Megajoules — frequently asked questions
How many megajoules are in a joule?
One joule equals 1e-06 MJ. MJ = J × 1e-06
What is the formula to convert joules to megajoules?
The formula is MJ = J × 1e-06. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert megajoules back to joules?
Divide instead of multiplying: one megajoule is 1,000,000 J. The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this joules to megajoules free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
What people search for
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 19, 2026 · Calculation runs client-side · No data collected · Report an error