Body mass index (BMI) is a number based on a person's weight and height that provides a way to estimate the effect of weight on health. The higher the BMI, the greater the risk of some diseases, including high blood pressure, coronary artery disease, stroke, osteoarthritis, some cancers, and type 2 diabetes.

To calculate exact BMI, one of the following equations is used:

• The person's weight in kilograms and height in metres: BMI = kilograms divided by (metres squared)
• The person's weight in pounds and height in inches: BMI = (pounds x 703) divided by (inches squared)