Understand pediatric BMI percentiles — how BMI is interpreted differently for children ages 2–20 using CDC growth charts, and what the numbers mean for your child's health.
CDC growth chart categories for children and teens (ages 2–20)
Use our free BMI calculator to check body mass index in both imperial and metric units. For children, always discuss results with your pediatrician.
Open BMI Calculator →Adult BMI uses fixed cutoff values: a BMI of 18.5–24.9 is healthy for every adult regardless of age or sex. For children, this approach fails because children's bodies change dramatically between ages 2 and 20 — in height, weight, muscle composition, bone density, and fat distribution. A BMI of 17 may be healthy for a 5-year-old but indicate underweight in a 15-year-old. A BMI of 22 might be overweight for an 8-year-old but perfectly healthy for a 17-year-old.
To account for this, the CDC developed sex-specific BMI-for-age growth charts based on a representative US sample of children measured in 1963–1965, 1966–1970, and 1988–1994. These charts plot a child's BMI against all other children of the same age and sex, producing a percentile ranking. The percentile tells you where a child falls relative to their peers — not whether they're individually "healthy" in an absolute sense.
Children below the 5th percentile are considered underweight relative to their peers. This doesn't necessarily indicate illness — some children are naturally lean due to genetics, high activity levels, or fast metabolism. However, children who are underweight may not be getting adequate nutrition for normal growth and development. Evaluation by a pediatrician is recommended, and tracking growth trends over time is more informative than a single measurement.
This is the target range. A child at the 60th percentile, for example, has a higher BMI than 60% of children of the same age and sex in the reference population. The healthy range is intentionally broad because natural variation in body size, frame, and composition is normal throughout childhood and adolescence. A child consistently in this range who is growing normally and is active and energetic is generally considered to be at a healthy weight.
Children in this range have a BMI higher than 85–94% of their peers. At this level, pediatricians typically recommend lifestyle assessment — evaluating diet quality, physical activity, screen time, and sleep — and may track more closely without immediate intervention. A single measurement at the 87th percentile in an active, growing child may resolve without intervention as growth continues.
Children at or above the 95th percentile are classified as obese, with elevated risk of developing metabolic syndrome, type 2 diabetes, hypertension, and sleep apnea even in childhood. Clinicians often further distinguish "severe obesity" as a BMI at or above 120% of the 95th percentile, as this level carries particularly elevated health risks. Pediatric obesity is now epidemic in the US, with approximately 19% of children ages 2–19 classified as obese.
Children don't grow at constant rates. During growth spurts, children often gain weight before gaining height, temporarily pushing their BMI percentile upward. This is a normal and expected pattern. Parents and caregivers should be careful not to over-interpret a single BMI measurement that may simply reflect the weight portion of a growth spurt that hasn't yet translated into height. Pediatricians monitor growth across multiple visits to identify meaningful trends.
CDC BMI-for-age charts were developed based on US population data and may not be equally appropriate for all ethnic and racial groups. Research has shown that, for example, Asian children may carry metabolically significant fat at lower BMI percentiles than children of European ancestry. Additionally, highly athletic children may have elevated BMI from muscle mass, similar to the issue seen with adult male athletes. A pediatric BMI number is a starting point for conversation — not a definitive health verdict.
The formula is the same (weight/height²), but results are expressed as age-and-sex-specific percentiles using CDC growth charts rather than fixed cutoffs. The same BMI number has different meanings at different ages and for different sexes.
Underweight: <5th percentile | Healthy: 5th–85th percentile | Overweight: 85th–95th percentile | Obese: ≥95th percentile. These are sex-specific and apply to ages 2–19.
Not necessarily. Growth spurts, muscle development, and frame size can all affect percentile readings. Pediatricians evaluate BMI trends over time alongside activity level, growth patterns, and family history — not a single snapshot.
CDC charts (2000) are recommended for children ages 2–19 in the US. WHO charts are recommended for infants under age 2 and are based on a multinational sample raised in optimal conditions. Both are sex-specific and use percentile-based interpretation.