Joules to Calories
Convert joule to calorie instantly — type a value and read the result, with the exact formula shown.
Reviewed by the CalcCafe editorial team · Last updated 1 July 2026 · How we test our tools
Example
1 J = 0.2390057 cal, 5 J = 1.195029 cal, 10 J = 2.390057 cal.
Common conversions: joule to calorie
Quick reference for the J → cal values you are most likely to need, computed with the exact factor the converter above uses. It includes the specific values people most often look up (100 J, 4.184 J, 1 J, 1,000 J, 4,184 J).
| Joule (J) | Calorie (cal) |
|---|
| 1 J | 0.239006 cal |
| 2 J | 0.478011 cal |
| 3 J | 0.717017 cal |
| 4.18 J | 0.999044 cal |
| 4.184 J | 1 cal |
| 5 J | 1.195 cal |
| 10 J | 2.3901 cal |
| 15 J | 3.5851 cal |
| 20 J | 4.7801 cal |
| 25 J | 5.9751 cal |
| 30 J | 7.1702 cal |
| 40 J | 9.5602 cal |
| 50 J | 11.9503 cal |
| 60 J | 14.3403 cal |
| 70 J | 16.7304 cal |
| 75 J | 17.9254 cal |
| 80 J | 19.1205 cal |
| 90 J | 21.5105 cal |
| 100 J | 23.9006 cal |
| 150 J | 35.8509 cal |
| 200 J | 47.8011 cal |
| 250 J | 59.7514 cal |
| 500 J | 119.5029 cal |
| 1,000 J | 239.0057 cal |
| 4,184 J | 1,000 cal |
Calorie to Joule
| Calorie (cal) | Joule (J) |
|---|
| 1 cal | 4.184 J |
| 5 cal | 20.92 J |
| 10 cal | 41.84 J |
| 50 cal | 209.2 J |
| 100 cal | 418.4 J |
How it works
Calorie = Joule × 0.2390057. Every value is converted through a single joule base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Converting joules to calories comes up most often in two settings: physics and chemistry coursework, where energy is measured in joules but reaction enthalpies are tabulated in calories, and energy-content work, where bomb-calorimeter readings or scientific data sheets report figures in joules that you want expressed in the more familiar calorie. The joule is the SI unit of energy, defined from kilograms, metres and seconds, while the calorie predates the SI system and was originally pinned to the heat needed to warm one gram of water by one degree Celsius.
The exact factor depends on which calorie you mean. This page uses the thermochemical calorie, which is defined as exactly 4.184 joules, so one joule equals 1 ÷ 4.184 = 0.2390057 cal. A handy rule of thumb: divide joules by 4 to get a slightly high calorie estimate, or shift the decimal and take roughly a quarter — 100 J is about 24 cal, and 1,000 J lands near 239 cal.
The most common mistake is confusing this small calorie with the food Calorie. The energy label on food uses the kilocalorie (1 Cal = 1,000 cal = 4,184 J), so a 250 J snack of energy is trivial, but a 250 Calorie snack equals over a million joules. If you are working from nutrition data, convert to kilocalories instead. Also watch the calorie variant: the International Table calorie (4.1868 J) gives a marginally different result of 0.238846 cal per joule, so cite which definition you used in scientific writing.
Frequently asked questions
How do you convert joule to calorie?
Multiply the number of joules by 0.2390057 to get calories. For example, 1 J = 0.2390057 cal.
What is 1 joule in calories?
1 joule equals 0.2390057 calories (1 J = 0.2390057 cal).
How many joules are in 1 calorie?
There are 4.184 joules in 1 calorie.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
How many calories are in 100 joules?
100 joules equal about 23.9 calories (100 × 0.2390057 = 23.90057 cal), using the thermochemical calorie of 4.184 J.
Is a joule bigger or smaller than a calorie?
A joule is smaller. One calorie equals 4.184 joules, so it takes more than four joules to make a single calorie.
What is the difference between a calorie and a Calorie (kilocalorie)?
A lowercase calorie is the small or gram calorie (4.184 J), while a capital Calorie used on food labels is a kilocalorie, equal to 1,000 small calories or 4,184 J.
How do I convert joules to food (nutritional) Calories?
Divide joules by 4,184 because one food Calorie is a kilocalorie. For example, 8,368 J equals 2 nutritional Calories.
What is the formula to convert joules to calories?
Calories = joules × 0.2390057, which is the same as joules ÷ 4.184 for the thermochemical calorie.
Why are there different conversion factors for joules to calories?
There are several calorie definitions. The thermochemical calorie is exactly 4.184 J (0.2390057 cal/J), while the International Table calorie is 4.1868 J (0.238846 cal/J), giving slightly different results.
How many calories is 1000 joules (1 kilojoule)?
1,000 joules equal about 239 calories (1,000 × 0.2390057 = 239.0057 cal), or roughly 0.239 kilocalories.
Can I convert calories back to joules?
Yes. Multiply calories by 4.184 to get joules, so 10 cal equals 41.84 J.
Is 1 calorie 4.186 J?
4.186 J is a rounding of the International Steam Table calorie, which is defined as 4.1868 J, while the 15 °C calorie is 4.1855 J. This converter uses the thermochemical calorie of exactly 4.184 J, which is the value used in chemistry and on food labels. The difference between 4.184 and 4.186 is under 0.05 percent, so it only matters in precise laboratory work.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.