1. How to convert joules to calories
The conversion is a single multiplication: cal = J × 0.239005736138. Both units are defined
against the same base — the joule (J) — so the factor is fixed and the result
is exact to the precision shown.
Worked at the two values people ask for most: 1 J = 0.23900574 cal and
100 J = 23.900574 cal. Going the other way, J = cal × 4.184, so
1 cal = 4.184 J.
Results are given to eight significant figures. That is more precision than most jobs need — for a rough figure, treat 1 J as about 0.23900574 cal and adjust — but rounding early and multiplying afterwards is how a small error becomes a visible one, so the full figure is what the converter carries.
2. Joules to Calories conversion table
| Joules (J) | Calories (cal) |
|---|---|
| 1 J | 0.23900574 cal |
| 2 J | 0.47801147 cal |
| 5 J | 1.1950287 cal |
| 10 J | 2.3900574 cal |
| 25 J | 5.9751434 cal |
| 50 J | 11.950287 cal |
| 100 J | 23.900574 cal |
| 250 J | 59.751434 cal |
| 500 J | 119.50287 cal |
| 1,000 J | 239.00574 cal |
Every row is the same factor applied — nothing in the table is a special case, and any value in between behaves the same way. Type your own figure into the converter above and the Formula tile shows the arithmetic being used, so the result is checkable rather than taken on trust.
3. What the two units are
- Joules (J). One J is 1 J.
- Calories (cal). One cal is 4.184 J.
Both are converted through the joule (J): the value is multiplied by its own unit's factor to reach the base, then divided by the target unit's factor to leave it. No direct joules to calories factor has to exist or be kept correct, which is also why the converter can show the same value in all 10 energy units at once.
The calorie is two units: the food Calorie is a kilocalorie, and the physics calorie is a thousandth of it. This category uses kcal and kJ, the pair printed on nutrition labels, where 1 kcal is exactly 4.184 kJ by the thermochemical definition. A kilowatt-hour is exactly 3.6 MJ.
If the pair you actually want is not this one, the full unit converter runs every 10 energy units off the same factor table, along with 11 other categories of measurement.
4. Joules to Calories FAQs
How do I convert joules to calories?
Multiply by 0.239005736138. 1 J = 0.23900574 cal, and 100 J = 23.900574 cal. The factor is exact to the precision shown, so the only rounding is the one you choose to do at the end.
How many calories is 1 J?
1 J = 0.23900574 cal. The full formula is cal = J × 0.239005736138, and 1 cal = 4.184 J going the other way.
What is 100 J in cal?
100 J = 23.900574 cal. The table above works the same factor through 10 values, and the converter takes any figure you type — including decimals.
How do I convert cal to J?
J = cal × 4.184, so 1 cal = 4.184 J. Use the Swap button in the converter to reverse the direction without retyping the value.
Which calorie does this use?
The kilocalorie — the food Calorie, exactly 4.184 kJ by the thermochemical definition. The physics calorie is a thousandth of it, and both appear in the converter. A kilowatt-hour is exactly 3.6 MJ.
Is anything I type sent to a server?
No. The factor table ships with the page and every conversion runs in your browser. Nothing is uploaded, logged or written to storage, and the converter keeps working offline once the page has loaded.