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Convert calories to joules
Instant, accurate cal → J conversion with a live converter, table and formula.
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1 calorie = 4.184 joules
1 joule = 0.239006 calories
calories to joules table
| calories (cal) | joules (J) |
|---|---|
| 0.5 | 2.092 |
| 1 | 4.184 |
| 2 | 8.368 |
| 5 | 20.92 |
| 10 | 41.84 |
| 20 | 83.68 |
| 50 | 209.2 |
| 100 | 418.4 |
| 500 | 2092 |
| 1000 | 4184 |
Formula
joules = calories × 4.184.
Example
10 calories = 41.84 joules.
What is a calorie?
A calorie (cal) is the energy to heat 1 g of water by 1°C (4.184 J).
What is a joule?
The joule (J) is the SI unit of energy.
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 | calories | joules |
|---|---|---|
| AA battery | 3,678 cal | 15,390 J |
| Smartphone battery (13 Wh) | 11,185 cal | 46,800 J |
| Apple (52 kcal) | 52,000 cal | 218,000 J |
| Daily diet (2,000 kcal) | 2,000,000 cal | 8,370,000 J |
| 1 kWh (unit of electricity) | 860,000 cal | 3,600,000 J |
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 joules in a calories?+
1 calorie = 4.184 joules.
How do I convert calories to joules?+
Enter the value in the calories box above and the joules value appears instantly. You can also type in the joules box to convert the other way.
Is this cal to J converter free?+
Yes — it is 100% free, needs no sign-up, and runs entirely in your browser.