Energy converter
Joules to Calories
Joules and Calories measure the same quantity in different unit systems. The relationship is 1 J = 0.23900574 cal, which gives 0.23900574 cal per J. Below you can convert any value, check a worked example and read the full chart.
Formula 1 J = 0.23900574 cal
Need the other direction? Calories to Joules.
How to convert Joules to Calories
The joule is the SI unit of energy, equal to one newton-metre. The small calorie is 4.184 joules; the food Calorie is a kilocalorie.
To convert Joules to Calories, multiply the value in J by 0.23900574. For example, 10 J × 0.23900574 = 2.390057 cal. This works because the ratio between the two units is constant for every value in energy.
Worked examples
| J | cal |
|---|---|
| 1 J | 0.23900574 cal |
| 2.5 J | 0.59751434 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 |
Reverse conversion
| cal | J |
|---|---|
| 1 cal | 4.184 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 |
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 J is 239.005736 cal.
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.
J to cal 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.
| Joules (J) | Calories (cal) |
|---|---|
| 1 J | 0.23900574 cal |
| 2 J | 0.47801147 cal |
| 3 J | 0.71701721 cal |
| 4 J | 0.95602294 cal |
| 5 J | 1.195029 cal |
| 6 J | 1.434034 cal |
| 7 J | 1.67304 cal |
| 8 J | 1.912046 cal |
| 9 J | 2.151052 cal |
| 10 J | 2.390057 cal |
| 11 J | 2.629063 cal |
| 12 J | 2.868069 cal |
| 13 J | 3.107075 cal |
| 14 J | 3.34608 cal |
| 15 J | 3.585086 cal |
| 16 J | 3.824092 cal |
| 17 J | 4.063098 cal |
| 18 J | 4.302103 cal |
| 19 J | 4.541109 cal |
| 20 J | 4.780115 cal |
| 21 J | 5.01912 cal |
| 22 J | 5.258126 cal |
| 23 J | 5.497132 cal |
| 24 J | 5.736138 cal |
| 25 J | 5.975143 cal |
| 26 J | 6.214149 cal |
| 27 J | 6.453155 cal |
| 28 J | 6.692161 cal |
| 29 J | 6.931166 cal |
| 30 J | 7.170172 cal |
| 31 J | 7.409178 cal |
| 32 J | 7.648184 cal |
| 33 J | 7.887189 cal |
| 34 J | 8.126195 cal |
| 35 J | 8.365201 cal |
| 36 J | 8.604207 cal |
| 37 J | 8.843212 cal |
| 38 J | 9.082218 cal |
| 39 J | 9.321224 cal |
| 40 J | 9.560229 cal |
| 41 J | 9.799235 cal |
| 42 J | 10.038241 cal |
| 43 J | 10.277247 cal |
| 44 J | 10.516252 cal |
| 45 J | 10.755258 cal |
| 46 J | 10.994264 cal |
| 47 J | 11.23327 cal |
| 48 J | 11.472275 cal |
| 49 J | 11.711281 cal |
| 50 J | 11.950287 cal |
| 60 J | 14.340344 cal |
| 70 J | 16.730402 cal |
| 80 J | 19.120459 cal |
| 90 J | 21.510516 cal |
| 100 J | 23.900574 cal |
Frequently asked questions
How many Calories are in 1 Joules?
1 J equals 0.23900574 cal.
How do I convert Joules to Calories?
Multiply the J value by 0.23900574. Example: 25 J = 5.975143 cal.
What is 2.5 J in cal?
2.5 J = 0.59751434 cal.
Is the J to cal 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.