Calories to Joules Converter
Used in physics and chemistry, where the small calorie appears in older textbooks and lab data. For food labels, use kcal to kJ.
1 cal = 4.184 J
joules
1 cal = 4.184 J
How to convert calories to joules
Multiply the number of calories by 4.184.
Formula
J = cal × 4.184
Examples
- 1 cal × 4.184 = 4.184 J
- 50 cal × 4.184 = 209.2 J
- 1,000 cal × 4.184 = 4,184 J
Calories to joules conversion table
| Calories (cal) | Joules (J) |
|---|---|
| 1 | 4.184 |
| 2 | 8.368 |
| 5 | 20.92 |
| 10 | 41.84 |
| 20 | 83.68 |
| 50 | 209.2 |
| 100 | 418.4 |
| 200 | 836.8 |
| 250 | 1,046 |
| 500 | 2,092 |
| 1,000 | 4,184 |
| 5,000 | 20,920 |
| 10,000 | 41,840 |
Values rounded to 4 decimal places or 4 significant digits.
About calories
The calorie used here is the thermochemical calorie, exactly 4.184 joules: roughly the energy needed to warm one gram of water by 1 °C. Food labels that say "calories" actually mean kilocalories.
About joules
The joule is the SI unit of energy. One joule is the work done by a force of one newton over one meter, or one watt of power for one second.
Frequently asked questions
How many joules are in one calorie?
One calorie equals 4.184 joules.
How do I convert calories to joules?
Multiply the number of calories by 4.184. For example: 50 cal × 4.184 = 209.2 J.
How many calories are in one joule?
One joule equals 0.239 calories.
Is the cal to J conversion exact?
Yes. The factor follows directly from the official definitions of both units, so the only rounding is in how many decimals are displayed.