This measure of obesity divides your weight (in kilograms) by your height (in meters), and divides by your height (in meters) again. It relates your weight to your surface area.

You can calculate your BMI by using the National Heart, Lung, and Blood Institute's BMI Calculator. You can also calculate it yourself, by dividing your weight in pounds by your height in inches. Divide this number by your height in inches AGAIN. Now multiply by 705. See our section on what your BMI means for interpretation.