Convert Joules to Calories
One joule equals 0.239006 calories. Type any value to convert joules to calories instantly — with a full reference table below.
Convert Joules to Calories
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How to convert Joules to Calories
To convert joules to calories, multiply by 0.239006. One joule equals 0.239006 cal, and one calorie equals 4.184 J.
- Take the value in joules — for example 7.5 J.
- Multiply by 0.239006 (the number of calories in one joule).
- 7.5 × 0.239006 = 1.792543 cal.
Quick mental estimate: Divide the number of joules by 4.2 (within 0.4% of the exact answer).
Joules to Calories conversion table
| Joules | Calories |
|---|---|
| 1 J | 0.239006 cal |
| 2 J | 0.478011 cal |
| 5 J | 1.195029 cal |
| 10 J | 2.390057 cal |
| 20 J | 4.780115 cal |
| 50 J | 11.95029 cal |
| 100 J | 23.90057 cal |
| 200 J | 47.80115 cal |
| 500 J | 119.5029 cal |
| 1,000 J | 239.0057 cal |
| 2,000 J | 478.0115 cal |
| Calories | Joules |
|---|---|
| 1 cal | 4.184 J |
| 2 cal | 8.368 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 |
| 200 cal | 836.8 J |
| 500 cal | 2,092 J |
| 1,000 cal | 4,184 J |
| 2,000 cal | 8,368 J |
About converting Joules to Calories
Joules (J) and Calories (cal) are both units of energy. The exact factor is 1 J = 0.239006 cal, so multiply by 0.239006 to go from joules to calories (or divide to go back).
The conversion runs entirely in your browser. Need the reverse? Use the Calories to Joules converter, or the full unit converter for every unit at once.
Real-world energy in joules and calories
| Example | Joules | Calories |
|---|---|---|
| One food Calorie (kcal) | 4,184 J | 1,000 cal |
| A 100 W bulb running for one hour | 360,000 J | 86,042.07 cal |
| A smartphone battery (≈19 Wh) | ≈ 69,300 J | ≈ 16,563.1 cal |
“≈” marks typical values; the rest are defined or measured figures.
The units
The SI unit of energy: the work done by one newton over one metre.
Used for: Science and food labels (kJ).
The thermochemical calorie: exactly 4.184 J — energy to warm 1 g of water by about 1 °C.
Used for: Chemistry. Food 'Calories' are kilocalories.
The thermochemical calorie is exactly 4.184 J and a kilowatt-hour is exactly 3.6 MJ, so these factors are exact.