Convert Calories to Kilocalories

About converting Calories to Kilocalories

Calories (cal) and Kilocalories (kcal) are both units of energy, so converting between them is a single multiplication: multiply your Calories figure by 0.001. Ten Calories comes to 0.01 Kilocalories, and a hundred works out at 0.1 Kilocalories.

Rule of thumb: going from Calories to Kilocalories divides, so the figure always shrinks — it takes about 1,000 Calories to make a single Kilocalory. If your answer came out bigger, you have the conversion the wrong way round.

What is a Calory?

The calorie is the unit most likely to be misread, because there are two of them. The small calorie — the one this converter uses — is approximately the heat needed to warm a gram of water by one degree Celsius, and it is a tiny amount of energy. The "calories" printed on food labels are not these: a food Calorie, traditionally written with a capital C, is a thousand small calories, properly a kilocalorie. So a 2,000-calorie daily diet is really about 8.4 million small calories. Several slightly different calories were defined historically; the thermochemical calorie used here is fixed at exactly 4.184 joules.

What is a Kilocalory?

A kilocalorie is a thousand small calories, and it is what people actually mean when they say "calories" about food. Every figure on a nutrition label, every count on a menu board and every target in a diet app is a kilocalorie, even where the label just prints "cal" — a 2,000-calorie day is 2,000 kcal, not 2,000 calories in the physicist’s sense. The convention of capitalising the food unit as Calorie was meant to mark that difference, but it survives mostly in textbooks. Most of the world prints both kJ and kcal on packaging; the United States prints calories alone, which keeps the ambiguity alive.

To put both in perspective: an apple holds roughly 95,000 small calories, while a plain bagel runs to roughly 250 kilocalories.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Kilocalories to Calories converter, or browse all Energy converters.