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i 1 Dietary Calorie (kcal) = 4.184 Kilojoules (kJ)
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About

Energy content in food is measured differently depending on the region. While the United States primarily utilizes the large Calorie (kcal), most other countries and scientific communities rely on the Kilojoule (kJ), an SI unit of energy. This discrepancy often leads to confusion when interpreting nutrition labels on imported goods or scientific dietary studies.

The conversion is based on the thermochemical definition where one dietary Calorie (which is actually a kilocalorie) is equivalent to exactly 4.184 kilojoules. Precision is necessary here; rounding errors in cumulative diet tracking can lead to significant discrepancies in daily energy intake estimation. This tool facilitates the translation between these units, aiding dietitians, athletes, and travelers in maintaining consistent energy tracking regardless of labeling standards.

nutrition diet energy conversion kcal kilojoules

Formulas

The conversion relies on the specific heat capacity of water definition for the thermochemical calorie. The relationship is linear and constant.

E(kJ) = E(kcal) × 4.184

To reverse the calculation (Kilojoules to Calories):

E(kcal) = E(kJ)4.184

Reference Data

Food ItemQuantityEnergy (kcal)Energy (kJ)
Apple (Medium)182 g95397
Banana (Medium)118 g105439
Egg (Large, Boiled)50 g78326
Bread (Slice, White)30 g79330
Rice (Cooked, White)158 g205858
Chicken Breast (Roasted)100 g165690
Salmon (Cooked)100 g206862
Almonds28 g164686
Cheddar Cheese28 g115481
Milk (Whole)240 ml149623
Orange Juice240 ml112469
Potato (Baked)173 g161674
Avocado200 g3221347
Butter14 g102427
Olive Oil14 g119498

Frequently Asked Questions

In nutrition, the terms are often used interchangeably, but technically 1 dietary Calorie (capital C) equals 1 kilocalorie (kcal), which is 1,000 small calories (thermal calories). This tool assumes the input is dietary Calories (kcal).
The Kilojoule is the standard SI unit for energy used in Australia, New Zealand, and parts of Europe. It is derived from the amount of work required to move a mass, whereas the calorie is based on heating water.
Yes, for nutritional purposes, the thermochemical calorie definition (4.184 J) is the standard. There is a "15-degree calorie" (4.1855 J) used in physics, but it is not used for food energy labeling.
Divide the Kilojoule value by 4.184. For a rough estimate, you can divide by 4.2.