The Calorie used on food labels is equal to how many calories?

The food Calorie (capital "C") is actually a kilocalorie ($1 \times {10}^{3}$ calories)!
Why would someone do this? Well, probably because it takes about 2 megacalories ($2 \times {10}^{6}$) to run a person for a day. So it is more convenient to talk about 2,000 Calories than it is to talk about 2 million calories.