# Glossary:Body mass index (BMI)

### From Statistics Explained

The **body mass index**, abbreviated as **BMI**, is a measure of a person’s weight relative to height that correlates fairly well with body fat. The BMI is accepted as the most useful indicator of obesity in adults when only weight and height data are available.

BMI is calculated by dividing body weight (in kilograms) by height (in metres) squared.

The following subdivisions are used to categorize the BMI into four categories:

- < 18.5: underweight;
- >= 18.5 and < 25: normal weight;
- >= 25 and < 30: overweight;
- >= 30: obese.

Note that the BMI is not calculated for children.