What is BMI and how is it used?

Body Mass Index (BMI) is a number calculated from a person’s weight and height. It is widely used as a reliable indicator of whether a person has a healthy body weight for their height. Specifically, BMI value categorizes a person to underweight, normal weight, overweight, or obese depending on what range the value falls in.

For example, let’s calculate BMI of a 176 cm tall, 80 kg man:

This is the World Health Organization’s (WHO) recommended body weight based on BMI values for adults (men and women, > 18 years).

CategoryBMI range – kg/m2
Severe Thinness< 16
Moderate Thinness16 – 17
Mild Thinness17 – 18.5
Normal18.5 – 25
Overweight25 – 30
Obese Class I30 – 35
Obese Class II35 – 40
Obese Class III> 40

BMI chart for adults

This is a graph of BMI categories based on the World Health Organization data: