Your body mass index (BMI) is a number based on your weight in relation to your height. It's a good measure of body fat and is helpful in screening for weight issues that may cause health problems.
For adults age 20 and over, BMI is determined using the same formula for men and women.
The calculation is slightly different for adolescents and adults. To determine the BMI for anyone under 20, use the BMI calculator provided by the Centers for Disease Control and Prevention.
For adults, here's how to calculate your body mass index:
Divide your weight in pounds by your height in inches squared, then multiply that number by 703.
Weight in Pounds ÷ (Height in Inches Squared) x 703 = BMI
For example, someone who is 160 pounds and 5’ 8” (68 inches tall) would use this formula:
160 ÷ (68 x 68) x 703 = 23.4
This person would first calculate their height in inches squared by multiplying 68 by 68, which equals 4,624. Next, he would divide 160 by 4,624, which equals 0.0346. He would finally multiply 0.346 by 703 for a BMI of 23.4, which would fall in the normal range.
What BMI says about your health
While BMI is a good measure of body composition, there are variables. For example, at the same BMI, women tend to have more body fat than men do. In addition, athletes at a normal weight may have a high BMI because they have more muscle.
According to the Centers for Disease Control and Prevention, those classified as being overweight or obese are at higher risk for many diseases and health conditions, including high blood pressure, high cholesterol, Type 2 diabetes, coronary heart disease, stroke, osteoarthritis, and some cancers and sleep disorders.
Even small steps in controlling your weight, such as increasing your activity and improving your eating habits, can benefit your health in a big way. They can also boost your energy, mood and physical ability.