Use this calorie calculator to determine the number of calories you would burn doing three activities of your choice. If you don't know your weight, you can estimate it. Then find the number of calories burned for the same three activities and the same amount of time by two people who weigh more or less than you. Enter the information in the table for yourself and the two other people. Describe the activities and the time spent doing them at the top of the three columns. Then enter the calories each person burns for each activity.