Calculators

BMI calculator

Calculate body mass index from height and weight, with WHO adult categories.

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  1. 1 Enter weight and height.
  2. 2 Switch units if you do not use metric.
  3. 3 Read the BMI and the adult category.

How it works

Body mass index is weight divided by height squared. Enter kilograms and centimetres, or switch to pounds and feet. The category labels follow the World Health Organization adult cut-offs. BMI does not measure fat directly and is a poor guide for children, athletes, and pregnancy.

BMI = kg / m²

Frequently asked questions

What ranges are used?

Below 18.5 is underweight, 18.5 to 24.9 is the usual adult range, 25 to 29.9 is overweight, and 30 or more is obese, using WHO adult cut-offs.

Is this a medical diagnosis?

No. It is a screening number. A clinician uses more than BMI.