How to convert calories to joules
One calorie equals 4.184 joules. To convert, multiply the number of calories by 4.184:
Mental-math shortcut: Multiply calories by 4.184. For food Calories (kcal), multiply by 4,184 — or use the kcal to kJ converter.
Example
Convert 100 calories to joules: 100 cal × 4.184 = 418.4 J.
Calories (small) to Joules conversion chart
| Calories (small) (cal) | Joules (J) |
|---|---|
| 1 | 4.184 |
| 2 | 8.368 |
| 5 | 20.92 |
| 10 | 41.84 |
| 50 | 209.2 |
| 100 | 418.4 |
| 239 | 999.98 |
| 500 | 2,092 |
| 1,000 | 4,184 |
| 10,000 | 41,840 |
What is a calorie?
A small calorie (cal) is the energy needed to warm one gram of water by 1 °C, defined as exactly 4.184 joules. It is used in chemistry and physics. The "Calories" on food labels are actually kilocalories: 1 food Calorie = 1 kcal = 1,000 small calories.
What is a joule?
The joule (J) is the SI unit of energy: the work done by a force of one newton over one meter, or one watt for one second. It is a small unit — lifting an apple about one meter takes roughly 1 J — so food energy is usually given in kilojoules.
Converting the other way? Use the Joules to Calories (small) converter.
Frequently asked questions
How many joules is one calorie?
One calorie is 4.184 joules.
How do I convert calories to joules?
Multiply the value in calories by 4.184. For example, 100 cal × 4.184 = 418.4 J.
What is 1 cal in joules?
1 cal is 4.184 joules.
How do I convert joules to calories?
Multiply joules by 0.239006 (or divide by 4.184). You can also use our Joules to Calories (small) converter.
Conversions use the internationally agreed definitions of each unit (for example, 1 inch = 2.54 cm exactly) and are rounded for display. Volume converters use US customary units unless stated otherwise.
Last updated: