BMI (body mass index) is a formula that uses both weight and height to estimate body fat. For most people, BMI provides a reasonable estimate of body fat. ( I used http://www.mayoclinic.com/health/bmi-calculator/NU00597)
I find it useful for metric for comparison. I can't compare my weight to yours as we have different body types, height etc. . However, if your BMI is in the 18.5 - 24.9 range and mine is 26, it would be a fair to say that you are in better shape than me.
Yep, BMI is horrible especially if you have any muscle on you. My BMI is 27 which is in the overweight range which I definitely am not. Edit: Really what you should be concerned with if you are trying to judge fitness level is body fat %.
