The BMI of Body Mass Index is a measurement based on a person's mass (measured in kilograms or pounds) and their height (measured in metres or inches). The BMI formula differs depending on whether you are using the metric or imperial system for your units of measure.  Below is the formula for calculating body mass index;
  For metric measurements use your height in kilograms divided by your height in metres (i.e 1.75) squared. An example would be a man who weighs 80kg and is 1.75m tall. The equation is 80kg/(1.75*1.75) = 80/3.06 = 26.1 which is classed in the overweight category. bmi-equation.png  
  We will use the same man as above but convert the units. 80kg = 176lbs and 1.75m (175cm) equates to 68.9 inches. In this case we divide the mass (176lbs) by our height in inches squared. 176/(68.9*68.9) = 176/4747.21 which = 0.037. Then we multiply by 703 which gives us 26.1 also.    
  Your Weight in Kilograms (kg): BMI:  
  Your Height In Centimeters (cm):  
  Your Weight in Pounds (lbs): BMI:  
  Your Height In Inches:  
  Very severely underweight less than 15
  Severely underweight from 15.0 to 16.0
  Underweight from 16.0 to 18.5
  Normal (healthy weight) from 18.5 to 25
  Overweight from 25 to 30
  Obese Class I (Moderately obese) from 30 to 35
  Obese Class II (Severely obese) from 35 to 40