1 calorie = 4.18 joules
1000 calories = 1 Calorie
The Calorie (with a capital C) is the nutritional calorie.
One joule is the work done, or energy expended, by a force of one newton moving one metre along the direction of the force. This quantity is also denoted as a newton metre with the symbol N x m.
1 J = 1 N x m
1 J = 1 kg x m^2 / s^2
The joule is also used in other types of measurements, such as coulombs and kilowatt hours.