What makes this calculator different? Well, its the compensation for your frame size. I thin skeleton person of 1.8m and a heavy skeleton person of 1.8m, weighing the same, obviously have a different percentage of fat. When using the calculator below and you choose "M" (medium) for you frame size, it calculates as normal. But if you choose "S" (small) or "L" (large) it will either compensate by either 10% up or down in the percentage body fat and the classification scale. This is a link to a frame size calculator.