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BMI for children and teens
For ages 2 to 19, BMI is read as a percentile for age and sex, not as a fixed number.
Children are still growing, so the adult cutoffs (18.5, 25, 30) do not apply. A child's BMI is calculated with the same formula as an adult's, then compared with other children of the same age and sex. The result is a percentile.
| BMI-for-age percentile | CDC category |
|---|---|
| Below the 5th | Underweight |
| 5th to below the 85th | Healthy weight |
| 85th to below the 95th | Overweight |
| 95th or higher | Obesity |
| 120% of the 95th or higher, or BMI of 35 or more | Severe obesity |
How to check a child's BMI
- Measure height and weight accurately, without shoes and in light clothing.
- Enter age, sex, height, and weight into the CDC child and teen BMI calculator, which returns the percentile and category.
Do not use the category shown by the calculator on our home page for anyone under 20. It uses adult cutoffs.
What the number does and does not mean
BMI percentile is a screening tool, not a diagnosis. Growth spurts, puberty timing, and build can all move a child's BMI for a while. A pattern over several visits tells a doctor more than one reading. If a result concerns you, talk with your child's pediatrician before making changes to food or activity.
For children under 2, BMI is not used. Doctors track weight-for-length on WHO growth charts instead.
Common questions
Can I use the adult BMI calculator for my teenager?
No. Teens are compared with others of the same age and sex using percentiles. Adult cutoffs can label a growing teen incorrectly.
What BMI percentile is healthy?
The CDC defines healthy weight as the 5th percentile up to, but not including, the 85th percentile.
Does a high percentile mean my child has a weight problem?
Not by itself. BMI is a screening tool. A pediatrician looks at growth over time, family history, and overall health before drawing conclusions.