Two Sizes, One Word
A small calorie (cal) is the energy to heat 1 gram of water by 1°C. A food Calorie (Cal, capital C) is actually a kilocalorie — 1,000 small calories. So when a label says '250 Calories', it means 250 kcal, or 250,000 small calories.
Converting to Kilojoules
Many countries label food in kilojoules as well. 1 kcal = 4.184 kJ, so a 250 Cal snack contains about 1,046 kJ. This is a fixed conversion.
Reference
| Label | kcal | kJ |
|---|---|---|
| 1 Cal (food) | 1 | 4.184 |
| 250 Cal | 250 | 1,046 |
| 2,000 Cal/day | 2,000 | 8,368 |