Joules to Calories Converter
Convert joules into small calories and food Calories (kcal), plus kilojoules and watt-hours.
How the conversion works
The calorie and the joule both measure energy. One thermochemical calorie equals 4.184 joules, so to convert joules to calories you divide by 4.184.
The food Calorie shown on nutrition labels is actually a kilocalorie (kcal) — 1,000 small calories, or 4,184 joules. This converter shows both so you can move between physics and nutrition units.
cal = J ÷ 4.184
kcal = J ÷ 41841 cal = 4.184 J · 1 kcal (food Calorie) = 4,184 J = 4.184 kJ
Conversion table
| Joules | Calories (cal) | Food Calories (kcal) |
|---|---|---|
| 100 J | 23.9 cal | 0.0239 kcal |
| 1,000 J | 239 cal | 0.239 kcal |
| 4,184 J | 1,000 cal | 1 kcal |
| 10,000 J | 2,390 cal | 2.39 kcal |
| 100,000 J | 23,901 cal | 23.9 kcal |
| 1,000,000 J | 239,006 cal | 239 kcal |
Frequently asked questions
How do you convert joules to calories?
Divide the energy in joules by 4.184 to get small calories, or by 4,184 to get food Calories (kcal). For example, 2,000 J ÷ 4.184 ≈ 478 cal ≈ 0.478 kcal.
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie — 1,000 small calories. So 1 food Calorie = 4,184 joules, while 1 small calorie = 4.184 joules.
How many joules are in a kilocalorie?
One kilocalorie (one food Calorie) equals 4,184 joules, or 4.184 kilojoules.