Why kcal, why not just cal?

[asallen]

Why on foodstuffs are calories prefixed with k? To me k means 1000. ie a kilogram is 1000 grams. Have I just eaten a 400,000 calorie sandwich? No wonder i weigh 17 stone!

[Gef]

Yes, you have just eaten a 400,000 calorie sandwich. A calorie is such a tiny amount of energy that it is much easier to give values for foods in kilocalories.

[bernardo]

A calorie is the amount of energy needed to heat 1 gramme of water by 1 degree Celsius.
A kilocalorie (also known as a Calorie [capital c]) is the amount of energy needed to heat 1 kg (1 litre) of water by 1 degree Celsius.
The confusion started when they changed from the centimetre-gram-second system to the metre-kilogramme-second system.

[secretspirit]

Only Elvis could have eaten a 400,000 calorie sandwich!