BMI calculator
Body Mass Index or BMI is a calculation that uses your weight and height to produce a number. That number can be used to indicate whether you are a healthy weight for your height. It is not an absolute measure of a person's health and not the only factor that must be considered but can be a useful starting point for assessing your weight and the implications of it on your health.
Use the calculators below to work out your BMI using metric or imperial measurements.
BMI formula
BMI is calculated by dividing your weight in kg, by the square of your height in metres squared:
weight (kg)
height (m) x height (m)
= kg/m
2
What is my BMI?
Insert your weight in kg and your height in cm in the boxes to calculate your BMI.
BMI classification
The terminology used in describing the categories for the different BMI ranges has evolved over the years but the values defining them have stayed the same.
Class 3 obesity is also called 'severe obesity' depending on which classification scale is being used. Either way an individual is defined as having the condition 'overweight' when their BMI is 25kg/m² or greater, and having the condition 'obesity' when their BMI is 30kg/m² or greater.
It is important to bear in mind that these ranges may vary depending on your family background, and in some groups the cut off numbers for 'overweight' and 'obesity' are lower.
Body Mass Index (BMI) Ranges (kg/m²)
18.5-24.9
Below 18.5
25.0-29.9
30.0-34.9
35.0-39.9
Above 40
Underweight
Healthy Weight
Overweight
Obesity Class 1
Obesity Class 2
Obesity Class 3
