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What Is BMI


Your BMI (body mass index) is a measure that uses your height and weight to estimate if your weight is within a healthy range.

The BMI calculation divides an adult's weight in kilograms by their height in metres squared.


For example, A BMI of 25 means 25kg/m2.

(source: NHS)

What Does BMI Mean


For most adults, an ideal healthy BMI is within the 18.5 to 25 range.

For children and young people aged 2 to 18, the BMI calculation will not be accurate.


If your BMI is:

  • Below 18.5 – you're in the underweight range.

  • Between 18.5 and 25– you're in the healthy weight range.

  • Between 25 and 30– you're in the overweight range.

  • Between 30 and 40– you're in the obese range.

The Accuracy Of BMI


BMI does take into account variations in body shape/size, giving an estimated healthy weight range for a particular height.

However, BMI is not the only factor that is taken into account when assessing if your a healthy weight.

Also, muscle is much denser than fat, so muscular people may actually be a healthy weight even though their BMI is classed as obese.

You should not use BMI as a measure if you're pregnant. This calculator is not set-up for people under the age 18.

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