BMI Percentile Calculator for Children (Ages 2-19)
Children's BMI is interpreted differently from adult BMI because body fatness changes with age and differs between boys and girls throughout childhood and adolescence. Instead of fixed cutoffs, the CDC and American Academy of Pediatrics use BMI-for-age percentiles derived from nationally representative growth chart data collected in 2000. A BMI percentile tells you how a child's BMI compares to other children of the same age and sex. The four weight-status categories are: underweight (below the 5th percentile), healthy weight (5th percentile to below the 85th), overweight (85th to below the 95th), and obese (95th percentile and above). These thresholds apply to children and teenagers aged 2 through 19 years. This calculator asks for the child's age in whole years, sex, and BMI value. It then interpolates between anchor-point values derived from CDC growth chart tables to estimate the percentile band. Because this tool uses simplified linear interpolation rather than the full LMS method, results are approximate. The CDC's own online tool uses the complete statistical model and will give a more precise figure. This calculator is for informational screening only and does not replace a clinical assessment by a pediatrician or other qualified healthcare provider.
CDC weight status: -- (--).
How the percentile is determined
The calculator interpolates linearly between the anchor ages in the CDC growth chart data to estimate the BMI values at the 5th, 85th, and 95th percentiles for the child's exact age. It then classifies the entered BMI against those three thresholds.
Interpolated P = P_low + (age - age_low) / (age_high - age_low) * (P_high - P_low)
Category: BMI < P5 = Underweight; P5 ≤ BMI < P85 = Healthy weight;
P85 ≤ BMI < P95 = Overweight; BMI ≥ P95 = Obese
Worked example
Boy, age 10, BMI 19.5:
- Anchor ages 10: P5 = 14.2, P85 = 19.0, P95 = 22.0 (boys)
- BMI 19.5 is at or above P85 (19.0) and below P95 (22.0)
- Result: Overweight (at or above the 85th percentile, below the 95th percentile)
CDC BMI-for-age anchor points (simplified)
| Age | Boys P5 | Boys P85 | Boys P95 | Girls P5 | Girls P85 | Girls P95 |
|---|---|---|---|---|---|---|
| 2 | 14.7 | 17.0 | 18.0 | 14.2 | 17.0 | 18.0 |
| 5 | 13.8 | 16.5 | 17.9 | 13.6 | 16.8 | 18.4 |
| 8 | 13.5 | 18.0 | 21.0 | 13.4 | 18.3 | 21.3 |
| 10 | 14.2 | 19.0 | 22.0 | 14.0 | 19.4 | 22.8 |
| 12 | 14.8 | 20.5 | 23.5 | 14.8 | 21.0 | 24.5 |
| 15 | 16.0 | 22.9 | 26.2 | 16.0 | 23.5 | 27.5 |
| 18 | 17.5 | 24.5 | 28.5 | 17.7 | 25.2 | 29.2 |
Source: CDC BMI-for-age growth charts (2000). Values are approximate anchor points used for linear interpolation. For ages outside this table (19 years) the nearest anchor is used. The CDC online calculator applies the full LMS statistical method to the complete data set.
CDC weight status categories for children
| Weight status | BMI-for-age percentile |
|---|---|
| Underweight | Below the 5th percentile |
| Healthy weight | 5th percentile to below the 85th percentile |
| Overweight | 85th percentile to below the 95th percentile |
| Obese | 95th percentile and above |
These categories are consistent with guidelines from the CDC, the American Academy of Pediatrics, and the American Academy of Family Physicians. BMI-for-age is a screening tool, not a clinical diagnosis. A child in the overweight or obese range should be evaluated by a healthcare provider who can assess diet, activity level, growth trajectory, family history, and other clinical factors.
BMI percentile calculator: frequently asked questions
What is a BMI percentile for children?
A BMI percentile compares a child's BMI to other children of the same age and sex using CDC reference data from the 2000 growth charts. For example, a child at the 60th percentile has a BMI equal to or greater than 60% of children the same age and sex. Unlike adult BMI, which uses fixed cutoffs, children's weight status is always expressed as a percentile because BMI changes significantly with age during growth.
What BMI percentile is considered healthy for a child?
The CDC defines healthy weight for children aged 2 to 19 as a BMI-for-age at or above the 5th percentile and below the 85th percentile. Below the 5th percentile is classified as underweight. At or above the 85th percentile and below the 95th percentile is overweight. At or above the 95th percentile is obese. These categories are the same for both boys and girls, though the underlying BMI values differ by age and sex.
Is a child's BMI percentile the same as an adult BMI category?
No. Adult BMI categories use fixed thresholds (for example, overweight is 25.0 to 29.9 for all adults). Children's BMI categories use age- and sex-specific percentile cutoffs because BMI normally fluctuates throughout childhood and puberty. A BMI of 18 may be in the healthy range for a 10-year-old boy but borderline underweight for a 17-year-old. Always use an age- and sex-specific growth chart for children.
How accurate is this BMI percentile lookup?
This tool uses simplified anchor-point data derived from CDC BMI-for-age growth charts, with linear interpolation between anchor ages. Results are approximate and are intended for informational screening purposes only. The CDC online calculator uses the full LMS statistical method applied to the complete 2000 growth chart data set, which will produce more precise percentile values. Consult a pediatrician for clinical assessment.
Can BMI percentile be used to diagnose obesity in children?
No. BMI percentile is a screening tool, not a diagnostic measure. A child at or above the 95th percentile is classified as obese by CDC convention, but a full clinical assessment by a healthcare provider is required to diagnose obesity and plan any intervention. BMI does not directly measure body fat, and factors such as muscle mass, bone density, ethnicity, and pubertal stage all affect interpretation.
Official sources
- CDC BMI for Children and Teens: CDC BMI Calculator for Child and Teen.
- CDC Growth Charts: CDC Clinical Growth Charts.
- American Academy of Pediatrics: AAP.org.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. General information, not medical advice.