Body mass index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. It is calculated by dividing weight in kilograms (kg) by height in meters squared (m2). For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 22.86.
BMI is used to screen for weight-related health problems such as obesity, underweight, and eating disorders. It is also used to track weight loss or gain. The World Health Organization (WHO) classifies BMI into five categories: underweight, normal weight, overweight, obese, and severely obese.