Health & Medical Adolescent Health


Updated September 29, 2014.


BMI, or Body Mass Index, is a value that is used to screen for body fatness. BMI is calculated using a person's height and weight.

In metric values, BMI is weight in kilograms divided by height in meters squared, or:
BMI = weight (kg) / [height (m)]2

In U.S. values, BMI is weight in pounds divided by height in inches squared multiplied by 703, or:
BMI = weight (lb) / [height (in)]2 x 703

Once the BMI value is calculated for a teen, the number is used to get a percentile based on a BMI chart that is for either males or females.

Once a percentile is obtained, you can determine if your teen is underweight, healthy weight, overweight or obese:
  • In the 5th percentile or below: underweight
  • Within the 5th to 85th percentile: healthy weight
  • Within the 5th to 85th percentile: overweight
  • 95th percentile or above: obese

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