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Conversion Formula:
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The conversion between kilojoules (kJ) and calories is a fundamental calculation in nutrition and energy science. One calorie (small calorie) is defined as the amount of energy needed to raise the temperature of 1 gram of water by 1°C, while one kilojoule is 1000 joules in the International System of Units.
The calculator uses the following simple formula:
Where:
Explanation: The conversion factor 4.184 comes from the definition of the thermochemical calorie, which is the most commonly used conversion in nutritional contexts.
Details: While most countries use kilojoules for food energy labeling, many people are more familiar with calories. This conversion helps in understanding and comparing energy values in different unit systems.
Tips: Simply enter the kilojoules value you want to convert. The calculator will automatically compute the equivalent calories. All values must be positive numbers.
Q1: What's the difference between calories and Calories (with capital C)?
A: 1 Calorie (kilocalorie) = 1000 calories. Food labels typically use Calories (capital C), which are actually kilocalories.
Q2: Why do some sources use 4.1868 instead of 4.184?
A: 4.184 is the thermochemical calorie, while 4.1868 is the international steam table calorie. The difference is negligible for most practical purposes.
Q3: How accurate is this conversion?
A: The conversion is mathematically exact based on the defined relationship between joules and calories.
Q4: Which countries use kJ vs. kcal on food labels?
A: The US uses kcal (Calories), while EU, Australia, and others use kJ, often with kcal in parentheses.
Q5: How many kJ/calories should a person consume daily?
A: Average adult needs about 8,700 kJ (2,000 kcal) per day, but this varies by age, gender, weight, and activity level.