Unlike as in adults, Body Mass Index (BMI) for children is age and sex specific. It is often referred to as BMI-for-age.

The method of calculating BMI in children is the same as in adults but is compared to the typical values of children of the same age and sex.

In children, there are no set thresholds for BMI as in adults. In other words, the BMI percentile allows for comparison with other children of the same age and sex.

In children, body weight classifications are different from those of adults because body composition goes on changing as the child grows.  Furthermore, the body composition differs between boys and girls basically due to the differences in sexual development.


There is no definition of percentile that is universally accepted. It can be best described as a score of comparison. It is commonly used in testing all kinds of data.

According to the CDC National Center for Health Statistics, the BMI height and weight percentiles of the child or adolescent show how the child compares with other children of the same age and sex.

For example if the child is 75th percentile of height, it means that the child is taller than 75% of the children of the same age and sex.

Similarly if the child is, say, 40th percentile for weight, it means that the child weighs more than 40% of the children of the same age and sex.

The BMI percentile calculations and values are same for kids and adolescents of all ages between 2 years to 20 years.

  • BMI 1st to 4th percentile indicates an underweight kid.
  • BMI 5th to 84th indicates a kid of healthy weight.
  • BMI 85th to 94th indicates an overweight kid.
  • BMI 95th to 100th indicates an obese kid..

Therefore, looking at the percentile score can tell you where your kid stands and if it denotes that your kid is underweight, or overweight or obese, you need to take action accordingly.

BMI percentile chart for children and teens

Chart showing BMI for children and teens

BMI percentile and Health Risks in Children

  • A BMI percentile indicating an overweight child is at risk of graduating to obesity.
  • A BMI percentile indicating an obese child is at a greater risk of dying prematurely due cardiovascular disease, cancer, diabetes and hypertension.

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