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Am I overweight or obese?

It is difficult to accurately calculate how much body fat an individual is carrying. A simple guide has been developed called Body Mass Index (BMI).

Body Mass Index

This is calculated using a mathematical formula - dividing your weight in kilograms by your height squared, in metres. This may sound complicated, but a BMI calculator is included on this website to work out your BMI for you.

People often question whether a BMI is accurate - does it take into account whether someone is 'big-boned' or muscular? It does - that is why the range for a healthy BMI is so big. However, as you get older, BMI may underestimate your risk of being overweight, because a greater proportion of your body weight will be fatty tissue rather than muscle. But whatever your situation, remember that BMI is just a rough guide to health risks. If you’re unsure about how this affects you, please speak to your GP.

Remember if your BMI is:

less than 18.5 you may be underweight
from 18.5 to 24.9 you are at a good weight
from 25 to 29.9 you are overweight
30 or higher you are obese


For children and young people who are not fully grown, a healthy BMI depends on their age. There is a separate children and young people's BMI calculator on this website, which takes this into account so that you can check your whole family's BMI as well as your own.

Waist circumference

Another way an adult can decide if they are overweight or obese is by measuring their waist. Of course, people come in many different shapes, it can be difficult deciding where your waist is, and the waistline of trousers can be very low or quite high. The simplest method of deciding where to measure your waist is by measuring around your body at your belly-button.

  • For women, a waist size over 35 inches (88 centimetres) is indicative of obesity
  • For men, a waist size over 40 inches (102 centimetres) is indicative of obesity

Information for South Asians

It does not matter how tall you are, or how muscular or how 'big-boned', none of these affect the accuracy of waist measurements in showing if you are overweight or obese, and fat stored around the stomach is the most dangerous for health.

To calculate a BMI use the links below:

Adults' BMI calculator

Child or Young Person's BMI calculator

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