Body mass index (BMI) is a measure of body fat based on height and weight. It is calculated by dividing weight in kilograms (kg) by the square of height in meters (m). For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 22.8.
BMI is a simple and inexpensive way to screen for underweight, overweight, and obesity. It is also used to track weight loss or gain over time. BMI was developed in the 19th century by Adolphe Quetelet, a Belgian statistician.