Exactly Raub. These online BMI "calculations" are so innacurate its ridiculous. There are three ways to get accurate body mass measurements. #1 is to go the exact way of getting lowered into a tank of water and exhaling all your air through a respirator. #2 is what we call "the egg". You sit in it and breathe through a tube and have all the air removed from the area you are sitting in. Basically the same as #1 but not as accurate. #3 is a bone scan that is expensive and takes a long damn time and is very accurate. The thicker your bones are the longer it takes since it has to scan your entire body. If you move the computer gets thrown off some since your bones aren't where they are supposed to be.