How do you calculate kilocalories?

The term, "Calorie" goes back to 1824, when it was used as a measure of energy. Since then, it's been replaced in most scientific usage with the joule. However, in Nutrition, it lives on -- kinda. Let me explain:

The original "calorie" (note the lower-case "c") was roughly the amount of energy required to raise the temperature of 1 gram of water by 1 degree C. For Nutrition, this is a tiny amount of energy -- so small it's nearly useless. So when people talked energy and Nutrition, they started using the Calorie (note the upper-case "C"), which was meant to refer to the amount of energy required to raise 1 kilogram of water by 1C degree. This is known as a Large Calorie, a Calorie, or a kilocalorie (note the lower case "c" in "kilocalorie) or Kcal.

So 1 Calorie = 1 Kcal = 1,000 calories.