How to Convert Megajoules to Kilojoules (MJ to kJ)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert megajoules into kilojoules by hand, with examples and a quick-reference table.
The conversion
To convert megajoules to kilojoules, multiply the value by 1,000. To go the other way, divide by the same number (or multiply by 0.001). For a quick estimate, multiply by about 1,000.
Kilojoules = megajoules × 1,000
Worked examples
- 3 MJ = 3,000 kJ
- 12.5 MJ = 12,500 kJ
- 75 MJ = 75,000 kJ
Megajoules to Kilojoules table
| Megajoules | Kilojoules |
|---|---|
| 1 MJ | 1,000 kJ |
| 2 MJ | 2,000 kJ |
| 5 MJ | 5,000 kJ |
| 10 MJ | 10,000 kJ |
| 20 MJ | 20,000 kJ |
| 25 MJ | 25,000 kJ |
| 50 MJ | 50,000 kJ |
| 100 MJ | 100,000 kJ |
| 250 MJ | 250,000 kJ |
| 500 MJ | 500,000 kJ |
| 1,000 MJ | 1,000,000 kJ |
Common questions
Is MJ to kJ exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilojoules to Megajoules converter.
Mistakes to avoid
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For any value, use the Megajoules to Kilojoules Converter or browse all energy converters.
Run your own numbers: Megajoules to Kilojoules Converter