### What's the difference between calories and kcal

• What are the differences between Calories, calories, and kcals?

Why do we have different terms to describe the same concept?

In what cases is it useful to use one unit of measurement over the other?

I just found this out now. This is really bad science and the health science community should be ashamed of themselves.

I am still not sure what the difference is between kcal and calorie. The explanations seem to say they are the same ...if that is true, why the long explanation?

@Rose Food packaging uses 'calories' as the label when they really should use 'Calories' (ie with capital C) or Kcal.

10 years ago

One calorie (with a lower case c) is the amount of energy required to heat 1 gram of water by 1°C. A kilocalorie is 1000 calories, and Calorie (with a capital C) and kilocalorie (Kcal) are synonyms. On food labels, nutrition facts are in terms of kilocalories/Calories. (Wikipedia)

Just like with grams vs. kilograms, units are used in a way that the number most readable. Putting nutrition labels in calories would take up quite a bit of extra space. I'm not sure how the Calorie/kilocalorie synonym came about, but I can guess it was for convenience. We use kilocalories much more frequently than calories for every day measurement, and kilocalories is quite a cumbersome word.

Right. The physics calorie (little "c" = 4.187 Joules) is an inconveniently small unit for talking about fueling the human body.

https://www.quora.com/Food-and-nutrition-Why-do-people-write-calories-when-it-actually-is-kilocalories-Eg-1-avocado-is-300-calories-I-guess-it-is-one-thousand-times-of-that-figure answer suggests originally Calorie was intended to be the energy that it takes to heat 1 kg of water by 1C, but when converting to joules it is more convenient to use one thousandth of that value, so scientists redefined calorie to mean the energy it takes to heat 1g of water by 1C. Scientists and European standards adopted this definition, hence why food labels say kcal, but Americans and speech didn't adopt this