How to convert calories to joules
- Take the value in calories.
- Use the formula joules = calories × 4.184.
- For example, 1 cal is 4.18 J.
About calories and joules
Multiply calories by 4.184 to get joules. The factor is exact because the thermochemical calorie is defined as 4.184 J. For a quick estimate multiply by 4 and add 5%.
Chemistry and physics problems often give heat in small calories, while SI units call for joules. If your number comes from a food label, it is in kilocalories, so multiply by 4,184 instead, or use the kcal to kJ page.
Examples
- 1 cal (warming 1 g of water by 1 °C) is 4.18 J
- 80 cal (melting 1 g of ice, roughly) is 334.72 J
- 540 cal (boiling away 1 g of water at 100 °C, roughly) is 2,259.36 J
- 1,000 cal (one food Calorie (kcal)) is 4,184 J
Calories to joules chart
| Calories | Joules (J) |
|---|---|
| 1 | 4.18 |
| 2 | 8.37 |
| 5 | 20.92 |
| 10 | 41.84 |
| 20 | 83.68 |
| 50 | 209.2 |
| 80 | 334.72 |
| 100 | 418.4 |
| 200 | 836.8 |
| Calories | Joules (J) |
|---|---|
| 250 | 1,046 |
| 500 | 2,092 |
| 540 | 2,259.36 |
| 1,000 | 4,184 |
| 2,000 | 8,368 |
| 5,000 | 20,920 |
| 10,000 | 41,840 |
| 100,000 | 418,400 |