Convert calories to megajoules

1 cal=4.1840e-6MJ

Use the converter below to change any calories value into megajoules instantly — with formula, conversion table, and real-world examples.

You have

Equals

4.1840e-6

Conversion formula

Forward

megajoules = calories × 4.1840e-6

Reverse

calories = megajoules × 239,005.74

Example: 10 cal × 4.1840e-6 = 4.1840e-5 MJ.

About both units

From

Calorie

cal

The gram calorie (small calorie) equals 4.184 joules — the energy to raise 1 g of water by 1 °C. It is a scientific unit, distinct from the nutrition "Calorie" (kcal). Largely replaced by joules in modern science.

Real-world: Raising 1 g of water 1 °C: 1 cal. A 100 kcal snack = 100,000 small calories.

Read full calorie reference →

Megajoule

The megajoule equals 1,000,000 joules. Used for fuel energy content, large-scale mechanical work and in some European natural-gas billing. A litre of petrol contains about 34 MJ of energy.

Real-world: 1 L petrol: ~34 MJ. 1 L diesel: ~38 MJ. Tesla Model 3 full charge: ~270 MJ.

Read full megajoule reference →

Calorie to Megajoule conversion table

Common calories to megajoules values for quick reference.

Calorie (cal)	Megajoule (MJ)
1 cal	4.1840e-6 MJ
10 cal	4.1840e-5 MJ
100 cal	0.0004184 MJ
500 cal	0.002092 MJ
1,000 cal	0.004184 MJ
5,000 cal	0.02092 MJ
10,000 cal	0.04184 MJ
50,000 cal	0.2092 MJ
100,000 cal	0.4184 MJ
500,000 cal	2.092 MJ

Tips & common mistakes

Quick tips

1 cal = 4.184 J. 1 kcal = 4184 J.
Scientific "calorie" and nutrition "Calorie" differ by 1000×.
Prefer joules in modern scientific writing.

Avoid these

Assuming "calories" on food labels means gram calories — they are kcal.
Mixing gram calories and kilocalories in calculations.
Confusing calorie (energy) with calorimeter (apparatus).

Frequently asked questions

How many megajoules in a calorie?

One calorie equals 4.1840e-6 megajoules.

How do I convert calories to megajoules?

Multiply the calorie value by 4.1840e-6 to get the equivalent in megajoules.

What is 100 calories in megajoules?

100 calories equals 0.0004184 megajoules.

Is a calorie bigger than a megajoule?

No. 1 calorie equals 4.1840e-6 megajoules, so one calorie is smaller.

How to convert calories to megajoules without a calculator?

Multiply by 0 for a quick estimate; use a calculator for precise results.

Related energy conversions

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