Free food maths tool

kJ to kcal Converter

Type an amount, pick whether it is in kilojoules or kilocalories, and get the other. One kilocalorie is 4.184 kilojoules, exactly.

Worked example

2,000 kcal is 8,368 kJ (1 kcal = 4.184 kJ).

Convert kilojoules and kilocalories

The result below starts from the example's numbers. Change any field and it updates as you type.

Track this target every day

Use the number above as your daily goal in CalorTracker, then log meals by photo, voice or text and see where your day stands against it. Free to start, no card needed to explore.

Results are estimates from published formulas, not medical advice. Your own body can sit above or below them.

Where the formulas come from, and how we check them: how we calculate.

The formula

kJ = kcal × 4.184
kcal = kJ ÷ 4.184

The factor is the definition of the thermochemical calorie: one calorie is exactly 4.184 joules, so one kilocalorie is exactly 4.184 kilojoules. It is not a measured value and has no rounding in it. The joint FAO/WHO/UNU expert consultation on human energy requirements (2001) expresses energy in both units and converts at this factor. Check: 2,000 kcal is 8,368 kJ.

Calories, kilocalories and Calories

On a food label in the United States, "Calories" with a capital C means kilocalories, and so does "cal" when it is used loosely for food. A small calorie (one gram of water by one degree) is a thousandth of that and is not used for food. When a label shows both numbers, the kilojoule figure is the kilocalorie figure times 4.184, and the two may differ by a digit because each is rounded for printing.

Want to turn the number into a daily target? The calorie calculator works in kilocalories. Food energy is also what this site's food pages list per 100 g, in kilocalories.

Common values in both units

The left pair converts kilocalories to kilojoules; the right pair converts round kilojoule figures, of the kind food labels print, to kilocalories.

kcal to kJ for common amounts
kcal	kJ	kJ	kcal
50	209	100	23.9
100	418	250	59.8
250	1,046	500	119.5
500	2,092	1,000	239
1,000	4,184	2,000	478
1,500	6,276	4,000	956
2,000	8,368	8,000	1,912
2,500	10,460	10,000	2,390.1

Frequently asked questions

How do I convert kJ to kcal?

Divide the kilojoules by 4.184. For example 1,000 kJ is about 239 kcal.

How do I convert kcal to kJ?

Multiply the kilocalories by 4.184. For example 2,000 kcal is 8,368 kJ.

Is a Calorie the same as a kilocalorie?

Yes. The Calories on a food label are kilocalories. One of them is 4.184 kilojoules.

Why is my label's kJ not exactly 4.184 times the kcal?

Each number on a label is rounded to a whole number or a few digits, and a maker may calculate energy in kilojoules directly. The two usually agree to within a rounding step.