How Do I Calculcate BMI?


Measure your height using a tape measure. This can be an easy way to measure height in inches. If you do not have a tape measure but know your height in feet and inches, you can convert it to total inches. Multiply your height in feet by 12 (the number of inches in a foot) and then add any additional inches. For example, a woman who is 5'5" would multiply 5 (her height in feet) by 12 to total 60 (i.e., 5 x 12 = 60). Then she would add the additional 5 inches of height for her total height in inches, which is 65 (i.e., 60 + 5 = 65).


Square the total of your height in inches, or multiply your height in inches by itself. For example, the woman who is 5'5" tall has a total height of 65 inches. Sixty-five inches squared is 4225 (i.e., 65 x 65 = 4225).


Weigh yourself on a scale to determine your body weight in pounds.


Multiply weight in pounds by 703. For example, a woman who weighs 115 pounds would multiply 115 by 703, which totals 80,845 (i.e., 115 x 703 = 80,845).


Divide the total of the body weight x 703 (from Step 4) by the squared total of height in inches (from Step 2). The woman who weighs 115 pounds would divide 80,845 by 4225, which equals 19.13 (i.e., 80845 / 4225 = 19.13). This individual would fall in the category of normal weight. See Resources for more information about BMI weight categories.

Tips and Warnings

  • There are online calculators available to determine BMI. One is available through the National Institutes of Health (see Resources).