Kilojoules to Calories Converter

Convert kilojoules to kilocalories (food Calories) or vice versa, with the relationship to small calories (cal) and common food energy examples.

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Kilojoules
100
kJ
Kilocalories
23.9
kcal (food Calories)
Small calories
23,900
cal
Food context
FoodkcalkJ
Apple (medium)95398
Slice of bread (white)80335
Banana (medium)90377
Mars bar (51 g)2601088
Boiled egg (large)70293
Conversion reference
1 kcal = 4.184 kJ  ·  1 kJ = 0.239 kcal  ·  1 kcal = 1,000 cal

"Calories" shown on food and drink labels are kilocalories (kcal), not small calories (cal). 1 kcal = 4.184 kJ = 1,000 cal. Values are rounded and intended as a guide only.

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Kilojoules to Calories Converter

Food packaging uses kilojoules (kJ) and kilocalories (kcal) to express energy content — but which unit means what, and how do they relate? In Australia and the EU, kJ often appears as the primary label; in the US and UK, kcal (called "Calories" with a capital C) dominates. This converter handles both directions and explains the three energy units you are likely to encounter.

Understanding kJ, kcal, and cal

Three units of energy appear on food labels and in nutrition literature. The kilocalorie (kcal) is the familiar "Calorie" on US food labels — note the capital C. It is the energy required to raise 1 kg of water by 1°C. The kilojoule (kJ) is the SI unit of energy used in Australian, European, and scientific contexts. The conversion factor is 1 kcal = 4.184 kJ, derived from the specific heat capacity of water. The small calorie (cal, lowercase) is 1/1000 of a kcal and appears mainly in chemistry; it is never used on food labels.

A standard adult daily energy intake of around 2,000 kcal is approximately 8,368 kJ. The Australian dietary guidelines recommend 8,700 kJ for an average adult, which is almost exactly 2,079 kcal — close enough that "roughly 2,000 kcal" and "roughly 8,700 kJ" refer to the same target. When reading imported food labels, always check which unit is being used for the headline number.

Frequently asked questions

Why do some food labels show both kJ and kcal?

EU regulations require both kJ and kcal to be shown on food labels. Australian labels require kJ as the primary unit but often include kcal. US labels show kcal as "Calories". When travelling or using imported foods, checking which unit is shown prevents significant misreading — a 1,000 kJ snack is only 239 kcal, not 1,000 kcal.

Is a calorie on a food label the same as a calorie in chemistry?

No. The "calorie" on a food label is actually a kilocalorie (kcal) — 1,000 times larger than the small calorie (cal) used in chemistry. This convention originated because the small calorie was impractically small for describing food energy. A 200-calorie chocolate bar contains 200 kcal = 200,000 cal = 836.8 kJ.

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