Millijoule is 0.001 joule units.
Millijoules to Calories Converter — mJ to cal
Convert Millijoule (mJ) to Calorie (cal) using the exact conversion factor (1 millijoule = 0.0002390057 calorie). See the formula, worked examples, conversion table, history, and common uses.
Millijoules to Calories converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
A thermochemical calorie is 4.184 joules.
Result = input x 0.001 / 4.184.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Millijoules to Calories
Millijoule and Calorie both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Millijoule is 0.001 joule units, and a thermochemical calorie is 4.184 joules.
Formula
calories = millijoules × 0.000239005736138
This factor comes from each unit's defined relationship to the category's base unit: 1 millijoule equals 0.001 base units, and 1 calorie equals 4.184 base units, so dividing one by the other gives the direct millijoule-to-calorie factor of 0.000239005736138.
Simple example
1 mJ × 0.0002390057361 = 0.0002390057 cal
1 millijoule = 0.0002390057 calories.
Real-world example
100 mJ × 0.0002390057361 = 0.0239005736 cal
100 millijoules = 0.0239005736 calories.
Conversion table
| Millijoule (mJ) | Calorie (cal) |
|---|---|
| 1 mJ | 0.0002390057 cal |
| 10 mJ | 0.0023900574 cal |
| 100 mJ | 0.0239005736 cal |
| 500 mJ | 0.1195028681 cal |
| 1,000 mJ | 0.2390057361 cal |
| 2,000 mJ | 0.4780114723 cal |
Reverse conversion: Calorie to Millijoule
0.0002390057 cal × 4184 = 0.9999998488 mJ
0.0002390057 calories = 0.9999998488 millijoules.
millijoules = calories × 4184
For a page dedicated to this direction, see Calorie to Millijoule.
Understanding the Millijoule (mJ)
Millijoule is 0.001 joule units.
Understanding the Calorie
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Where it's used: Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie')
Calorie vs. Calorie (kilocalorie). Food labels' capitalized 'Calorie' is actually one kilocalorie (1,000 small calories) — a long-standing labeling convention that causes frequent confusion.
Uses of the Calorie today
- Food energy labeling (as kilocalories, often written 'Calories')
- Historical chemistry and thermodynamics contexts
History of the Calorie
The calorie was originally defined in the early 19th century as the heat needed to raise one gram of water by one degree Celsius, but different scientific traditions defined it at slightly different reference temperatures, producing several close but non-identical 'calorie' values historically (15 °C calorie, mean calorie, thermochemical calorie).
To resolve this ambiguity, the thermochemical calorie was fixed by convention at exactly 4.184 joules; the very similar International Table calorie is fixed at exactly 4.1868 joules. The nutritional 'Calorie' seen on food labels is actually a kilocalorie (1,000 calories).
Historical origin. Calorie was not the invention of a single named person; it developed through the process described above.
Calorie — sources
- NIST Special Publication 811 — Documents the thermochemical calorie's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many calories are in 1 millijoule?
1 millijoule equals 0.0002390057 calories, using the exact defined conversion factor rather than an estimate.
How do I convert millijoule to calorie?
Multiply the millijoule value by 0.0002390057361. The converter above does this instantly to whatever precision you set.
How do I convert calorie back to millijoule?
Use the reverse factor: 1 calorie equals 4,184 millijoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a millijoule?
Millijoule (mJ) is a unit of energy.
What is a calorie?
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Is the millijoule to calorie conversion exact?
Yes. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between calorie vs. calorie (kilocalorie)?
Food labels' capitalized 'Calorie' is actually one kilocalorie (1,000 small calories) — a long-standing labeling convention that causes frequent confusion.