Calories to joules
Multiply calories by 4.184 to get joules.
50 cal = 209.2 J
How to convert calories to joules
The joule is the SI unit of energy, one newton-metre (one watt for one second). The calorie is the thermochemical calorie, exactly 4.184 joules.
Worked example — 50 cal: 50 × 4.184 = 209.2 J.
Calories to joules table
| Calories | Joules |
|---|---|
| 1 cal | 4.184 J |
| 5 cal | 20.92 J |
| 10 cal | 41.84 J |
| 25 cal | 104.6 J |
| 50 cal | 209.2 J |
| 100 cal | 418.4 J |
| 250 cal | 1,046 J |
| 500 cal | 2,092 J |
| 1,000 cal | 4,184 J |
Reverse and related
About calories and joules
Calorie (cal)
1 cal = 4.184 JDefinition. The thermochemical calorie, exactly 4.184 joules
History and origin
The calorie was defined in the nineteenth century as the heat needed to raise one gram of water by one degree Celsius; the thermochemical calorie is now fixed at exactly 4.184 joules.
Current use
Calories are used in chemistry and to describe small amounts of energy; food labels use the larger kilocalorie.
Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)
Joule (J)
1 J = 0.239006 calDefinition. The SI unit of energy, one newton-metre (one watt for one second)
History and origin
The joule is the SI unit of energy, named after James Prescott Joule, who showed in the 1840s that heat and mechanical work are equivalent. It is the work done by one newton acting over one metre.
Current use
Joules are the standard energy unit in physics and appear on appliance and equipment ratings.
Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)
Where people use this
Calories: chemistry, small energy amounts. Joules: physics, appliance ratings. 1 calorie is exactly 4.184 J.
Every value is carried to full double precision; the display is rounded.
Both units are defined in NIST SP 811, Appendix B; ISO 80000-5 (energy).
Questions people ask
How many joules in a calorie?
One thermochemical calorie is exactly 4.184 joules.
How many joules is 100 calories?
100 calories is 418.4 joules.
Is a calorie the same as a food Calorie?
No — a food Calorie is a kilocalorie, 1000 of these small calories.