Energy converter
Calories to Joules
Converting Calories to Joules is a single multiplication when you know the factor. One cal equals 4.184 J, so multiply the value in cal by 4.184. The calculator below works in both directions and accepts decimals.
Formula 1 cal = 4.184 J
Need the other direction? Joules to Calories.
How to convert Calories to Joules
The small calorie is 4.184 joules; the food Calorie is a kilocalorie. The joule is the SI unit of energy, equal to one newton-metre.
To convert Calories to Joules, multiply the value in cal by 4.184. For example, 10 cal × 4.184 = 41.84 J. This works because the ratio between the two units is constant for every value in energy.
Worked examples
| cal | J |
|---|---|
| 1 cal | 4.184 J |
| 2.5 cal | 10.46 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 |
Reverse conversion
| J | cal |
|---|---|
| 1 J | 0.23900574 cal |
| 5 J | 1.195029 cal |
| 10 J | 2.390057 cal |
| 25 J | 5.975143 cal |
| 50 J | 11.950287 cal |
| 100 J | 23.900574 cal |
When this conversion is useful
This is the calculation you need when you are comparing a nutrition label, an electricity bill or a heating system. Because the factor is fixed, you can use the same number for a single measurement or for a batch: 1,000 cal is 4,184 J.
Is the conversion exact?
Yes for practical use: the factors come from international definitions, with rounding applied only for display.
Reference: BIPM SI Brochure and NIST SP 811. Last reviewed: 2026-11-01.
cal to J conversion chart
The chart lists the most requested values. For a value that is not here, use the converter at the top of the page.
| Calories (cal) | Joules (J) |
|---|---|
| 1 cal | 4.184 J |
| 2 cal | 8.368 J |
| 3 cal | 12.552 J |
| 4 cal | 16.736 J |
| 5 cal | 20.92 J |
| 6 cal | 25.104 J |
| 7 cal | 29.288 J |
| 8 cal | 33.472 J |
| 9 cal | 37.656 J |
| 10 cal | 41.84 J |
| 11 cal | 46.024 J |
| 12 cal | 50.208 J |
| 13 cal | 54.392 J |
| 14 cal | 58.576 J |
| 15 cal | 62.76 J |
| 16 cal | 66.944 J |
| 17 cal | 71.128 J |
| 18 cal | 75.312 J |
| 19 cal | 79.496 J |
| 20 cal | 83.68 J |
| 21 cal | 87.864 J |
| 22 cal | 92.048 J |
| 23 cal | 96.232 J |
| 24 cal | 100.416 J |
| 25 cal | 104.6 J |
| 26 cal | 108.784 J |
| 27 cal | 112.968 J |
| 28 cal | 117.152 J |
| 29 cal | 121.336 J |
| 30 cal | 125.52 J |
| 31 cal | 129.704 J |
| 32 cal | 133.888 J |
| 33 cal | 138.072 J |
| 34 cal | 142.256 J |
| 35 cal | 146.44 J |
| 36 cal | 150.624 J |
| 37 cal | 154.808 J |
| 38 cal | 158.992 J |
| 39 cal | 163.176 J |
| 40 cal | 167.36 J |
| 41 cal | 171.544 J |
| 42 cal | 175.728 J |
| 43 cal | 179.912 J |
| 44 cal | 184.096 J |
| 45 cal | 188.28 J |
| 46 cal | 192.464 J |
| 47 cal | 196.648 J |
| 48 cal | 200.832 J |
| 49 cal | 205.016 J |
| 50 cal | 209.2 J |
| 60 cal | 251.04 J |
| 70 cal | 292.88 J |
| 80 cal | 334.72 J |
| 90 cal | 376.56 J |
| 100 cal | 418.4 J |
Frequently asked questions
How many Joules are in 1 Calories?
1 cal equals 4.184 J.
How do I convert Calories to Joules?
Multiply the cal value by 4.184. Example: 25 cal = 104.6 J.
What is 2.5 cal in J?
2.5 cal = 10.46 J.
Is the cal to J conversion exact?
Yes for practical use: the factors come from international definitions, with rounding applied only for display.
Does the calculator work offline?
Yes. The conversion runs in your browser with JavaScript, so it works after the page has loaded, even without a connection.