Calories to Joules Converter
Convert calories (cal) to joules (J) instantly. Type a value — the result updates as you type, and the swap button converts the other way.
Calories to Joules formula
J = cal × 4.184
1 calorie = 4.18 joules · 1 joule = 0.239 calories
To convert calories to joules, multiply the value by 4.184. For example, 100 cal:
J = 100 × 4.184J = 418.4
So 100 cal = 418.4 J.
Mental math shortcut
This conversion is exact, so there is no need to estimate: just multiply by 4.184.
Calories to Joules conversion table
Joules back to Calories
The same values converted the other way, rounded for everyday use:
| Joules | Calories |
|---|---|
| 4.18 J | 0.999 cal |
| 41.84 J | 10 cal |
| 209.2 J | 50 cal |
| 418.4 J | 100 cal |
| 999.98 J | 239 cal |
| 2092 J | 500 cal |
| 4184 J | 1000 cal |
About the units
Calories (cal)
The small (thermochemical) calorie is exactly 4.184 joules — the energy to warm 1 gram of water by about 1 °C.
Joules (J)
The joule is the SI unit of energy. One food Calorie (kcal) equals 4,184 joules.
Frequently asked questions
How many joules are in a calorie?
One calorie equals 4.18 joules.
What is 100 Calories in Joules?
100 cal = 418.4 J.
How do I convert Joules back to Calories?
Divide the joules by 4.184. Or use the Joules to Calories converter.