Megajoules to Calories
An instant megajoules-to-calories converter, with the formula and a reference table below.
| Megajoules | Calories |
|---|---|
| 1 MJ | 239005.736138 cal |
| 2 MJ | 478011.472275 cal |
| 3 MJ | 717017.208413 cal |
| 5 MJ | 1195028.680688 cal |
| 10 MJ | 2390057.361377 cal |
| 25 MJ | 5975143.403442 cal |
| 50 MJ | 11950286.806883 cal |
| 100 MJ | 23900573.613767 cal |
How to use
- Enter a value in the Megajoules field.
- The Calories figure appears immediately — no button to press.
- Typing in the Calories field converts back to Megajoules the same way.
- Use the reference table for the values that come up most often.
Megajoules to Calories formula
To convert megajoules to calories, multiply by 239005.736.
cal = MJ × 239005.736
Why this factor: the megajoule and the calorie are both defined against the joule, so dividing one definition by the other gives 239005.736 directly. Both definitions are set out in full below.
To go the other way, divide by 239005.736 — or use the Calories to Megajoules converter, which is the same calculation reversed.
Worked example
Take 500 MJ and multiply by the factor 239005.736: the result is 119502868.068834 cal.
500 MJ × 239005.736 = 119502868.068834 cal
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 calorie?
A calorie is the energy needed to warm one gram of water by one degree Celsius.
Definition: The thermochemical calorie is defined as exactly 4.184 joules.
Where it is used: Chemistry and physics literature, and older engineering references.
Worth knowing: The 'calories' on a nutrition label are actually kilocalories — 1,000 of these. A 500-Calorie meal is 500 kcal, or about 2.1 million joules.
Megajoules vs Calories
The megajoule is a metric unit while the calorie is a specialized 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 calories are in a megajoule?
One megajoule equals 239005.736 calories.
What is the formula to convert megajoules to calories?
Multiply the number of megajoules by 239005.736. To reverse it, divide by 239005.736 instead.
How do I convert calories back to megajoules?
Divide by 239005.736, which is the same as multiplying by 4.184e-06.
How many calories are in 10 megajoules?
10 MJ works out to 2390057.361377 cal.
Is there anything to watch out for with calories?
The 'calories' on a nutrition label are actually kilocalories — 1,000 of these. A 500-Calorie meal is 500 kcal, or about 2.1 million joules.
How is the megajoule defined?
Exactly 1×10⁶ joules. One kilowatt-hour is exactly 3.6 MJ.