The calorie calculator will give you a rough idea of how many calories you will burn off by getting active.
Whenever we move about we use extra energy. The heavier someone is, the more energy they use doing the same activity as someone lighter, and strenuous activities use up more energy than easier ones.
The amount of energy people use can vary widely even if they seem to be a similar build or age. The calculator is a rough guide to the number of calories you can use by doing different activities.