This BMI calculator is designed specifically for children and teens ages 2-20. Unlike adult BMI, children's BMI is interpreted using age and gender-specific percentiles.
BMI percentiles compare your child's BMI to other children of the same age and sex, providing a more accurate picture of their weight status during growth.
What is BMI for Children?
Just like in adults, BMI for children is calculated as the weight of a child in kilograms divided by the square of the height of a child in meters. The difference is that this resulting value is then compared to the BMI of children of the same age and gender.
A child that is at the 75th percentile has a BMI higher than 75% of children of the same age and gender. This method accounts for the natural variation in body composition as children grow.
BMI Percentile Categories
| Weight Status | Percentile Range |
|---|---|
| Underweight | Less than 5th percentile |
| Healthy Weight | 5th to 84th percentile |
| Overweight | 85th to 94th percentile |
| Obese | 95th percentile or greater |
Why Is Child BMI Different From Adult BMI?
Children's bodies undergo significant changes as they grow. Body fat levels will rise and fall throughout childhood and teenage years. Moreover, boys and girls develop in different ways. Using the adult BMI categories would misclassify many children who are perfectly healthy.
As an example, a 6-year old boy with a BMI of 20 is much more concerning than a 15-year old with a BMI of 20, and these can be compared to other children of the same age and gender using the percentile rankings provided by the CDC growth charts.
The CDC growth charts are based off data of children surveyed during the years prior to the obesity epidemic, representing a healthy population. Because of this, they help to identify children who may need special attention (such as nutritional guidance).
For adults 20 years and older, use our standard BMI calculator.