How to Determine BMI

Body mass index, or BMI, is a ratio of your weight to your height squared. A BMI under 18.5 is typically considered underweight while a BMI of 18.5 to 24.9 is categorized as a normal weight. An index of 25 to 29.9 is overweight and 30 or greater is obese. The ability to determine your BMI gives you a better idea of your risk for certain diseases. Being overweight or obese puts you at risk for developing type 2 diabetes, coronary heart disease, high LDL or bad cholesterol, stroke, hypertension, pregnancy complications and other ailments.

Step 1

Convert your weight from pounds to kilograms. Since 1 lb. equals approximately 0.454 kg, multiply your weight in pounds by 0.454. For example, a weight of 118 lbs. multiplied by 0.454 reflects a weight of 53.572 kg.

Step 2

Convert your height from inches to meters. Since there are 0.0254 meters per inch, multiply your height in inches by 0.0254 to get your height in meters. A height of 64 inches would convert to 1.6256 meters.

Step 3

Divide your weight in kg by your height in meters squared. For example, if your weight is 53.572 kg and your height is 1.6256 meters, divide 53.572 kg by 1.6256 meters squared or 2.6425. The resulting BMI is 20.3.