Body Mass Index for Adults

Weighing Scales

Body mass index (BMI) is a tool to estimate the normal weight range of a person based on their height. It is widely used to identify people who are overweight or obese and is a very approximate guide to the percentage of body fat. BMI is defined as body weight divided by the square of your height (in kilograms per square metre).

Use our online calculator to work out your body mass index by entering your height and weight below. You can use metric or imperial (British) units. The calculator will then tell you if you are underweight, normal weight or overweight. Be honest; nobody is watching!

A Body Mass Index between 18.5 and 25.0 is considered normal. BMI is only one of several factors which are used to assess health risks. If you have concerns about your weight, or how it might affect your general health and risk from disease, you should consult a qualified physician.