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Convert joules to calories
Instant, accurate J → cal conversion with a live converter, table and formula.
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1 joule = 0.239006 calories
1 calorie = 4.184 joules
joules to calories table
| joules (J) | calories (cal) |
|---|---|
| 0.5 | 0.119503 |
| 1 | 0.239006 |
| 2 | 0.478011 |
| 5 | 1.19503 |
| 10 | 2.39006 |
| 20 | 4.78011 |
| 50 | 11.9503 |
| 100 | 23.9006 |
| 500 | 119.503 |
| 1000 | 239.006 |
Formula
calories = joules × 0.239006.
Example
10 joules = 2.39006 calories.
What is a joule?
The joule (J) is the SI unit of energy.
What is a calorie?
A calorie (cal) is the energy to heat 1 g of water by 1°C (4.184 J).
Real-world reference points
A food Calorie is a kilocalorie: an apple is ~52 kcal, a daily diet ~2,000 kcal (~8.4 MJ).
| Reference | joules | calories |
|---|---|---|
| AA battery | 15,390 J | 3,678 cal |
| Smartphone battery (13 Wh) | 46,800 J | 11,185 cal |
| Apple (52 kcal) | 218,000 J | 52,000 cal |
| Daily diet (2,000 kcal) | 8,370,000 J | 2,000,000 cal |
| 1 kWh (unit of electricity) | 3,600,000 J | 860,000 cal |
Mistakes to avoid with energy conversions
- Food 'Calories' are kilocalories — mixing cal and kcal creates 1000× errors.
- Confusing kWh (energy) with kW (power) on bills and appliance labels.
- Comparing battery mAh across different voltages — energy needs Wh, not mAh alone.
Frequently asked questions
How many calories in a joules?+
1 joule = 0.239006 calories.
How do I convert joules to calories?+
Enter the value in the joules box above and the calories value appears instantly. You can also type in the calories box to convert the other way.
Is this J to cal converter free?+
Yes — it is 100% free, needs no sign-up, and runs entirely in your browser.