Convert calories to joules instantly. Enter a value below, or use the formula and reference table further down the page.
In practice
Calories to joules multiplies by 4.184 for a thermochemical calorie, the standard used in nutrition and chemistry. A food 'calorie' on a label is really a kilocalorie (kcal), equal to 4,184 joules, so a 200 kcal snack is about 837 kJ. Joules are the SI unit, so food labels in Europe and Australia list kilojoules alongside or instead of kilocalories. Take care with the word 'calorie': a small calorie (1 cal) is a thousand times smaller than the food Calorie, which can cause huge errors.
How to convert calories to joules
Multiply the value by 4.184.
J = cal × 4.184Example: 10 cal = 41.84 J.
Calories to Joules conversion table
| Calories (cal) | Joules (J) |
|---|---|
| 1 cal | 4.184 J |
| 2 cal | 8.368 J |
| 3 cal | 12.552 J |
| 4 cal | 16.736 J |
| 5 cal | 20.92 J |
| 10 cal | 41.84 J |
| 15 cal | 62.76 J |
| 20 cal | 83.68 J |
| 25 cal | 104.6 J |
| 50 cal | 209.2 J |
| 100 cal | 418.4 J |
Frequently asked questions
How many joules is 1 calorie?
1 calorie equals 4.184 joules.
What is the formula to convert cal to J?
To convert cal to J, multiply the value by 4.184. The full formula is: J = cal × 4.184.
How do I convert joules back to calories?
Use the same calculator above and type your value into the joules field instead — it converts in both directions. Or use the reverse formula: cal = J ÷ 4.184.
Is the cal to J conversion exact?
The conversion factor used here (4.184) is the standard internationally defined value. Results on this page are rounded to four decimal places for readability.