Convert Calories to Joules
Convert Calories to Joules instantly. 1 Calory (cal) equals 4.184 Joules (J).
Calories to Joules conversion table
| Calories (cal) | Joules (J) |
|---|---|
| 1 cal | 4.184 J |
| 2 cal | 8.368 J |
| 3 cal | 12.552 J |
| 5 cal | 20.92 J |
| 10 cal | 41.84 J |
| 20 cal | 83.68 J |
| 50 cal | 209.2 J |
| 100 cal | 418.4 J |
| 500 cal | 2,092 J |
| 1,000 cal | 4,184 J |
1 Calory = 4.184 Joules · multiply Calories by 4.184
About converting Calories to Joules
Calories (cal) and Joules (J) are both units of energy, so converting between them is a single multiplication: multiply your Calories figure by 4.184. Ten Calories comes to 41.84 Joules, and a hundred works out at 418.4 Joules.
Rule of thumb: going from Calories to Joules multiplies, so the figure always grows — one Calory is already 4.184 Joules. If your answer came out smaller, you have the conversion the wrong way round.
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.
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.
To put both in perspective: an apple holds roughly 95,000 small calories, while lifting an apple one metre takes about a joule.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Joules to Calories converter, or browse all Energy converters.
Frequently asked questions
How many Joules are in one Calory?
There are 4.184 Joules in one Calory.
How do I convert Calories to Joules?
Multiply the number of Calories by 4.184. For example, 10 Calories = 41.84 Joules.
What is 100 Calories in Joules?
100 Calories is equal to 418.4 Joules.
How do I convert Joules to Calories?
Multiply the Joules value by 0.239 (or divide by 4.184).
Is this Calories to Joules conversion exact?
Yes, exactly. Both units are fixed against the same base by definition, and 1 Calory = 4.184 Joules is the complete value — nothing is rounded away.
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.
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.