Body Mass Index: Background and Calculators

The Body Mass Index (BMI) is calculated by dividing your weight in kilograms (kg) by your height in meters squared (m)²

Use the convenient BMI calculators below

BMI = Weight (kg)/Height (m) ²

This body mass index is specifically called the Quetelet Body Mass Index, named after its creator and Belgian mathematician Lambert Quetelet (1796-1874).

The BMI is an easy way to estimate whether or not you are overweight or obese.  Roughly 2/3 of adult Americans have BMI values which put them into either the overweight or obese categories listed below.  Across a large population, the BMI correlates well with the degree of body fat.  However there are certain exceptions.  Very muscular, heavy athletes, despite having high BMI values, are quite lean when body fat is actually measured.  In older adults the BMI frequently underestimates the amount of body fat.  A BMI in the overweight or obese category significantly increases your risk for cardiovascular disease, type 2 diabetes, the metabolic syndrome, and various cancers.

Quetelet’s BMI is not designed for use with people aged 17 years or less.

BMI Categories:

• Underweight = less than 18.5
• Normal = 18.5-24.9
• Overweight = 25-29.9
• Obese = 30.0 or greater

Note: The calculators below will function only if your browser supports JavaScript (most do; try it).