Convert calories to joules
Converting calories to joules is a common energy task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 cal equals 4.184 J, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert calories to joules
To convert calories to joules, multiply the number of calories by 4.184. For example, 10 cal × 4.184 = 41.84 J.
J = cal × 4.184
- Write down the value in calories you want to convert.
- Multiply it by 4.184 (the exact cal→J factor).
- The result is your value in joules. Check it below with the converter or the table.
Conversion table
Common values of calories and their equivalents in joules:
| cal | J |
|---|---|
| 1 | 4.184 |
| 2 | 8.368 |
| 3 | 12.552 |
| 4 | 16.736 |
| 5 | 20.92 |
| 10 | 41.84 |
| 20 | 83.68 |
| 25 | 104.6 |
| 50 | 209.2 |
| 100 | 418.4 |
| 250 | 1,046 |
| 500 | 2,092 |
About these units
Calorie (cal). The small calorie is the energy needed to raise one gram of water by 1 °C, defined as exactly 4.184 joules. It is mostly used in chemistry and heat calculations.
Joule (J). The joule is the SI unit of energy: the work done by one newton acting over one meter. Food labels in most countries, physics and engineering use joules.
Frequently asked questions
How do I convert calories to joules?
To convert calories to joules, multiply the number of calories by 4.184. For example, 10 cal × 4.184 = 41.84 J. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many joules are in 1 calorie?
1 cal = 4.184 J. That is the fixed relationship used by this converter and by international standards.
How many calories are in 1 joule?
1 J = 0.239006 cal. If you are converting in the opposite direction, use our Joule to Calorie converter for the dedicated table and FAQ.
Is the calories to joules conversion exact?
Yes. Both units are defined by international agreement, so the factor of 4.184 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is calorie used for?
The small calorie is the energy needed to raise one gram of water by 1 °C, defined as exactly 4.184 joules. It is mostly used in chemistry and heat calculations.