Convert Joules to Calories
Convert Joules to Calories instantly. 1 Joule (J) equals 0.239 Calories (cal).
Joules to Calories conversion table
| Joules (J) | Calories (cal) |
|---|---|
| 1 J | 0.239 cal |
| 2 J | 0.478 cal |
| 3 J | 0.717 cal |
| 5 J | 1.195 cal |
| 10 J | 2.3901 cal |
| 20 J | 4.7801 cal |
| 50 J | 11.9503 cal |
| 100 J | 23.9006 cal |
| 500 J | 119.5029 cal |
| 1,000 J | 239.0057 cal |
1 Joule = 0.239 Calories · multiply Joules by 0.239
About converting Joules to Calories
Joules (J) and Calories (cal) are both units of energy, so converting between them is a single multiplication: multiply your Joules figure by 0.239. Ten Joules comes to 2.3901 Calories, and a hundred works out at 23.9006 Calories.
Rule of thumb: going from Joules to Calories divides, so the figure always shrinks — it takes about 4.184 Joules to make a single Calory. If your answer came out bigger, you have the conversion the wrong way round.
What is a Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.
What is a Calory?
The calorie is the unit most likely to be misread, because there are two of them. The small calorie — the one this converter uses — is approximately the heat needed to warm a gram of water by one degree Celsius, and it is a tiny amount of energy. The "calories" printed on food labels are not these: a food Calorie, traditionally written with a capital C, is a thousand small calories, properly a kilocalorie. So a 2,000-calorie daily diet is really about 8.4 million small calories. Several slightly different calories were defined historically; the thermochemical calorie used here is fixed at exactly 4.184 joules.
To put both in perspective: lifting an apple one metre takes about a joule, while an apple holds roughly 95,000 small calories.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Calories to Joules converter, or browse all Energy converters.
Frequently asked questions
How many Calories are in one Joule?
There are 0.239 Calories in one Joule.
How do I convert Joules to Calories?
Multiply the number of Joules by 0.239. For example, 10 Joules = 2.3901 Calories.
What is 100 Joules in Calories?
100 Joules is equal to 23.9006 Calories.
How do I convert Calories to Joules?
Multiply the Calories value by 4.184 (or divide by 0.239).
Is this Joules to Calories conversion exact?
The definition is exact — Joules and Calories are both fixed against the same base by international agreement — but the decimal shown here is rounded for readability, because the true ratio does not terminate. For engineering or scientific work, carry more decimal places than this page displays.
What is a Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.
What is a Calory?
The calorie is the unit most likely to be misread, because there are two of them. The small calorie — the one this converter uses — is approximately the heat needed to warm a gram of water by one degree Celsius, and it is a tiny amount of energy. The "calories" printed on food labels are not these: a food Calorie, traditionally written with a capital C, is a thousand small calories, properly a kilocalorie. So a 2,000-calorie daily diet is really about 8.4 million small calories. Several slightly different calories were defined historically; the thermochemical calorie used here is fixed at exactly 4.184 joules.