Convert kilocalorie to joule

The calorie of food labels is really the kilocalorie: 1 kcal = 1,000 cal = 4.1868 kJ, the heat that warms a kilogram of water by one degree. Nutrition labels in the EU must give both kJ and kcal, the US gives 'Calories' with a capital C meaning kcal, and the adult reference intake is 2,000 kcal, about 8,400 kJ. A slice of bread is around 80 kcal, an hour's brisk walk burns about 300.