Kilojoules to Calories
Convert kilojoule to calorie instantly — type a value and read the result, with the exact formula shown.
Example
1 kJ = 239.0057 cal, 5 kJ = 1,195.029 cal, 10 kJ = 2,390.057 cal.
How it works
Calorie = Kilojoule × 239.0057. Every value is converted through a single joule base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Kilojoule-to-calorie conversion shows up most often when people read nutrition labels. Australia, New Zealand, and most of Europe print food energy in kilojoules, while the United States and many calorie-counting apps still think in Calories — so a snack listed as 600 kJ needs converting before it fits a familiar daily target. The same math also appears in fitness trackers, exercise-machine displays, and physics or chemistry homework, where energy released or absorbed is quoted in one unit but needed in the other.
Both units are metric in spirit. The joule (and its multiple, the kilojoule) is the official SI unit of energy, defined from force times distance. The calorie predates SI and was originally defined as the heat needed to raise one gram of water by one degree Celsius; the modern "thermochemical" calorie is fixed at exactly 4.184 joules. This converter uses the small (gram) calorie, so 1 kJ = 239.0057 cal — a large number because one small calorie is a tiny amount of energy.
For a fast mental estimate, remember that 1 kJ is just under a quarter of a thousand small calories: multiply kilojoules by 239, or round to 240 for quick head math. If you instead want food Calories (kilocalories), the shortcut flips — divide kilojoules by about 4.2, so 600 kJ is roughly 143 kcal.
- The single biggest mistake is mixing up the lowercase "calorie" (cal) with the capital-C "Calorie" you see on food labels, which is actually a kilocalorie — 1,000 times larger. This page outputs small calories, so its results are 1,000× the food-Calorie figure for the same input.
Frequently asked questions
How do you convert kilojoule to calorie?
Multiply the number of kilojoules by 239.0057 to get calories. For example, 1 kJ = 239.0057 cal.
What is 1 kilojoule in calories?
1 kilojoule equals 239.0057 calories (1 kJ = 239.0057 cal).
How many kilojoules are in 1 calorie?
There are 0.004184 kilojoules in 1 calorie.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
Is a kilojoule the same as a calorie?
No. A kilojoule is the SI unit of energy, while a calorie is an older heat-based unit. One kilojoule equals 239.0057 small calories, or about 0.239 food Calories (kilocalories).
How many calories is 100 kJ?
100 kilojoules equals 23,900.57 small calories (cal). In food-Calorie terms that is about 23.9 kcal.
Why does this converter give such a large number of calories?
It reports small (gram) calories, where 1 kJ = 239.0057 cal. The number looks big because each small calorie is a tiny amount of energy; one food Calorie equals 1,000 of them.
How do I convert kilojoules to food Calories instead?
Divide kilojoules by 4.184 to get kilocalories (food Calories). For example, 2,000 kJ is about 478 kcal. This page's small-calorie result divided by 1,000 gives the same figure.
How many kilojoules are in a daily 2,000 Calorie diet?
A 2,000 food-Calorie diet is about 8,368 kJ, since each kilocalorie equals 4.184 kJ. Many labels round this to roughly 8,400 kJ.
What is 500 kJ in calories?
500 kilojoules equals 119,502.85 small calories (cal), or about 119.5 food Calories (kcal).
Is the kilojoule-to-calorie factor exact?
The underlying definition is exact: 1 thermochemical calorie equals exactly 4.184 joules, which gives 239.0057 cal per kJ. The displayed result is simply rounded for readability.
Which countries use kilojoules instead of calories on labels?
Australia, New Zealand, and most of the European Union show energy in kilojoules, with kilocalories often listed alongside. The United States primarily uses Calories, so converting helps compare products across regions.
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