Food energy is labelled as calories (kcal) in some countries and kilojoules (kJ) in others, so converting between them is a daily need for anyone reading international nutrition labels. The conversion is exact: 1 kcal = 4.184 kJ. This tool converts in both directions — type into either field and the other updates instantly.
How it works
Both units measure the same thing — food energy — so a single exact factor connects them. To convert calories to kilojoules the tool computes kJ = kcal × 4.184; to reverse it, kcal = kJ ÷ 4.184. The kilocalorie here is the food (large) calorie shown on labels, equal to 1,000 small calories. Because the factor is a definition, results are exact rather than rounded approximations.
Example
A snack listed as 100 kcal:
100 × 4.184 = 418.4 kJ
| Calories (kcal) | Kilojoules (kJ) |
|---|---|
| 50 | 209.2 |
| 100 | 418.4 |
| 250 | 1,046 |
| 2,000 | 8,368 |
So a 2,000 kcal daily intake equals about 8,368 kJ. Everything runs in your browser — no data leaves your device.