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How to calculate your BMI and why


Obesity is a common problem, estimated to affect around one in four adults and around one in five children (aged 10 to 11) in the UK. Knowing your BMI (Body Mass Index) can help you understand if you are a healthy weight or if you are obese or in danger of becoming obese.

The risks of obesity
Taking steps to tackle obesity is important because, in addition to causing obvious physical changes, it can contribute to a number of serious life-threatening conditions such as:

  • Type 2 Diabetes
  • Coronary Heart Disease
  • Some types of cancer, such as breast cancer and bowel cancer
  • Stroke


Obesity can also affect your quality of life and lead to psychological problems, such as low self-esteem or depression.

Calculating your BMI
BMI (Body Mass Index) is a measure of whether you are a healthy weight for your height.
BMI us not used to diagnose obesity definitively, as very muscular people sometimes have a high BMI due to muscle being denser than fat. However, for the majority of people, it can be a useful indication of whether they may be overweight.

How to calculate your BMI

BMI = weight √∑ height √∑height

For example:
Weight = 70kg
Height = 1.75m

Divide weight by height: 70 divided by 1.75 = 40
Divide the above sum by height again: 40 divided by 1.75 = 22.9

BMI = 22.9


For most adults, a healthy BMI is somewhere between 18.5 and 24.9.
Visit the NHS website to find out more.