Ans

Unit converter

Food calories to kilojoules.

Convert kcal to kJ and kJ to kcal. Type in either box and the other follows. Food labels carry both, because kilojoules are the SI figure and kilocalories are what people actually count.

kcal → kJExact definition
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Kilocalories to kilojoules — common values, to 6 significant figures.
kcalkJ
50 kcal209.2 kJ
100 kcal418.4 kJ
200 kcal836.8 kJ
300 kcal1255.2 kJ
400 kcal1673.6 kJ
500 kcal2092 kJ
750 kcal3138 kJ
1000 kcal4184 kJ
1500 kcal6276 kJ
2000 kcal8368 kJ
2500 kcal10460 kJ
1 kcal=4.184 kJ 1 kJ=0.2390057361 kcal

Definitions

  • The kilocalorie is 1000 small calories. It is what food labels and fitness apps mean when they say "calories".
  • The kilojoule is 1000 joules, and the energy unit on UK and EU nutrition labels alongside kilocalories.
  • This conversion is exact by definition. 1 kcal = 4.184 kJ.
  • The food calorie is the kilocalorie: 1 kcal = 1000 cal. Nutrition labels marked "calories" mean kcal.

How it works

One direction multiplies and the other divides by the same number, so nothing is lost by going back and forth.

The value passes through J, the unit every other energy unit on the site is defined against, rather than a number written into this page on its own. That is why the figure here, the figure in the table above and the general energy converter always agree.

Display precision limits significant figures rather than decimal places, because one fixed number of decimals is useless across a range this wide. Very large and very small results switch to scientific notation with a proper superscript exponent. The editable box always holds a plain number at full working precision, so you can carry on from either side.

Common questions this answers: how many kilojoules in a kilocalorie (food calorie) (4.184), how many kilocalories in a kilojoule (0.239006), and what 2000 kcal is in kilojoules (8368 kJ).

From the maker of Ans — a scientific calculator you can own. Same idea: a proper instrument, nothing in the way.