The Body Mass Index is a measure of body fat based on height and weight that applies to adult men and women.

Calculate your BMI with our metric and imperial BMI calculator.

Metric Units

Height (cm):

Weight (kg):


BMI, kg/m2 Weight
<18.5 Underweight
18.5–24.9 Normal weight
25.0–29.9 Overweight
30.0–34.9 Obese

Class 1
35.0–39.9 Class 2
≥40.0 Class 3



Adolphe Quetelet

The equation was originally created by Adolphe Quetelet, a Belgian, in 1832 as a method to define the standard proportions of the human build. Only in the last half century has the BMI been used as a means to determine body-fat percentage. Ancel Keys, a physiology professor, used Quetelet's equation as part of a 1972 published report on obesity and created the name body mass index or BMI. While widely used in population health studies, the BMI equation has been critiqued for its use in individual diagnoses for determining whether someone is overweight or obese.