Calories to Megajoules

Convert calories (cal) to megajoules (MJ). Type a value below to see the result update instantly. Reference table and formula included.

Calculator

Calories

cal

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Megajoules

1 cal = 4.1840e-6 MJ

Calories to Megajoules Conversion Table

Common values, ready to copy:

calories	megajoules
1 cal	4.1840e-6 MJ
2 cal	8.3680e-6 MJ
5 cal	2.0920e-5 MJ
10 cal	4.1840e-5 MJ
25 cal	0.000105 MJ
50 cal	0.000209 MJ
100 cal	0.000418 MJ
1,000 cal	0.004184 MJ

Formula

megajoules = calories × 0.000004184

Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.

About Calories and Megajoules

Calories (cal): Originally defined as the energy to raise one gram of water by one degree Celsius; exactly 4.184 J in the modern definition (the thermochemical calorie). Common uses: Scientific work in chemistry, where the small calorie is the natural unit for heat-of-reaction measurements.

Megajoules (MJ): A million joules; the unit for larger-scale energy quantities. Common uses: Daily food intake (a typical adult consumes 8-10 MJ per day), fuel energy content (gasoline ≈ 34 MJ per liter), and industrial energy.

How the conversion works

Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.

The exact relationship is megajoules = calories × 0.000004184, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.

When this conversion matters

Converting between calories and megajoules comes up wherever energy measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.