The body mass index (BMI) is a measure of an individual’s height / weight characteristics. BMI is commonly used as a way of estimating an individual’s body fat and categorising them into groups accordingly. In the UK, for adults (aged 18 or over), BMI is classified according to the table below.

BMI is calculated by taking an individual’s weight (in kilograms) and dividing it by their height (in metres) squared.
