How to convert joules to calories
Apply the documented joules-to-calories relationship below, keeping the full stored constant until the displayed result is rounded.
Joules × 0.2390057361 = Calories
For example, 10 J equals 2.39005736 cal.
Joules to Calories reference table
| Joules | Calories |
|---|---|
| 1 J | 0.23900574 cal |
| 5 J | 1.19502868 cal |
| 10 J | 2.39005736 cal |
| 25 J | 5.9751434 cal |
| 50 J | 11.95028681 cal |
| 100 J | 23.90057361 cal |
Method and quality checks
- Calculation
- Joules × 0.2390057361 = Calories. The calculator keeps the stored factor through the operation and rounds only the displayed result to the selected or page-supported precision.
- Unit convention
- The named energy convention is used exactly as labelled. Small calories, food Calories, and alternate BTU definitions must not be mixed.
- Input validation
- Finite numeric inputs are accepted. Results outside the supported numeric range are rejected instead of being displayed as valid measurements.
- Reasonableness check
- 10 J produces 2.39005736 cal. Check the direction and approximate scale before relying on a more precise displayed value.
Deeper method: How significant figures work.
Small calories are not food Calories
This converter uses the thermochemical calorie, a small calorie equal to exactly 4.184 joules. A food Calorie with an uppercase C is a kilocalorie and equals 1,000 small calories, so nutrition values must not be entered as though they were cal.
- Use cal for small thermochemical calories and kcal for kilocalories.
- One food Calorie equals 4,184 joules.
- Preserve the unit capitalization and context when sharing a result.
Reference: NIST energy conversion factors.