Calorie to kJ Converter
Convert food calories (kcal) to kilojoules for European nutrition labels, fitness tracking and diet planning. 1 kcal = 4.184 kJ, reference table for common foods.
Last updated: May 2026
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Converting kilocalories to kilojoules
Calories appear on US nutrition labels, while kilojoules are used on EU, UK and Australian labels. Use this converter when comparing the energy in a food across labels from different regions. kJ = kcal × 4.184
Energy in common foods
The values below show typical energy for standard servings. Use them as a reference when comparing labels across regions.
| Food | Serving | kcal | kJ |
|---|---|---|---|
| Apple, medium | 182 g | 95 | 398 |
| Banana, medium | 118 g | 105 | 439 |
| White bread, 1 slice | 30 g | 79 | 331 |
| Boiled egg | 50 g | 78 | 326 |
| Cheddar cheese | 30 g | 120 | 502 |
| Chicken breast, cooked | 100 g | 165 | 690 |
| White rice, cooked | 100 g | 130 | 544 |
| Whole milk | 240 ml | 149 | 623 |
| Olive oil, 1 tbsp | 14 g | 120 | 502 |
| Digestive biscuit | 15 g | 71 | 297 |
Daily intake reference: the common adult guideline of 2000 kcal equals 8368 kJ. Individual needs vary with age, weight and activity level.
Frequently Asked Questions
Why are there different energy units?
Different fields developed different energy measurements historically. Calories are used in nutrition, joules in physics, and kilowatt-hours in electricity. Converting between them is common.
What's the difference between calories and Calories?
A food Calorie (with capital C) is actually 1 kilocalorie (1000 calories with lowercase c). Nutrition labels use kilocalories, which is why food energy seems smaller than expected when converted to other units.
How do I quickly estimate kJ from kcal without a calculator?
Multiply kcal by 4 for a fast mental estimate. The exact factor is 4.184, so the shortcut runs about 4.4% low. For 500 kcal the estimate is 2000 kJ (precise value: 2092 kJ). For a quick label check this is close enough; use the converter above when precision matters.
Why do US nutrition labels use calories but European labels use kilojoules?
The FDA in the United States mandates calorie labeling on packaged food. Most of the rest of the world, including the EU, UK, Canada, and Australia, requires kilojoule labeling instead. This creates confusion when comparing products across borders. A 100-calorie snack is about 420 kJ; without conversion, European shoppers might think it's four times higher in energy. International brands have to relabel or modify their packaging for different markets.
Does cooking or food prep change the calorie count on the label?
The label shows calories for the food as sold (raw or cooked, depending on the product). Cooking can change water content and some nutrient availability, but the total energy content of the food itself doesn't change. If you weigh food after cooking, you might get a different calorie amount per gram because water evaporates, making it more concentrated. Converting calories to kJ doesn't change this, you need to account for weight changes separately.