Calculate BMI-for-age percentile for children and teens aged 2 to 20 using the official CDC 2000 growth chart LMS parameters, with the CDC weight status.
| Input | Result |
|---|---|
| 10-year-old, 140 cm, 32 kg | BMI 16.3 - about the 51st percentile |
| 10-year-old, 140 cm, 45 kg | BMI 23.0 - at or above the 95th percentile |
| 5-year-old, 110 cm, 18 kg | BMI 14.9 - about the 47th percentile |
| 15-year-old, 170 cm, 75 kg | BMI 26.0 - about the 93rd percentile |
A growth percentile compares your child with a reference population of the same age and sex — not with "normal". The 50th percentile is the median, not a target. A healthy child can sit steadily at the 10th percentile for years, and that is a different situation from a child who drops from the 60th to the 10th in six months.
This is why pediatric practice looks at the curve, not the number. A single measurement tells you where a child is; two or three measurements over time tell you how they are growing, which is the thing that actually carries information. Very few children track a constant percentile — most move up or down one band between visits and that is normal.
| BMI percentile for age and sex | CDC category |
|---|---|
| Below the 5th | Underweight |
| 5th to under the 85th | Healthy weight |
| 85th to under the 95th | Overweight |
| 95th or above | Obesity |
| 120% of the 95th percentile or above (or BMI 35+) | Severe obesity |
These are the reference values themselves, not estimates: the M column of the CDC LMS file is the 50th percentile, so this table is the published median for each age and sex. Whole-year ages are interpolated between the published monthly rows.
| Age | Boys | Girls |
|---|---|---|
| 2 years | 16.6 kg/m² | 16.4 kg/m² |
| 3 years | 16.0 kg/m² | 15.7 kg/m² |
| 4 years | 15.6 kg/m² | 15.3 kg/m² |
| 5 years | 15.4 kg/m² | 15.2 kg/m² |
| 6 years | 15.4 kg/m² | 15.2 kg/m² |
| 7 years | 15.5 kg/m² | 15.4 kg/m² |
| 8 years | 15.8 kg/m² | 15.8 kg/m² |
| 9 years | 16.1 kg/m² | 16.3 kg/m² |
| 10 years | 16.6 kg/m² | 16.8 kg/m² |
| 11 years | 17.2 kg/m² | 17.4 kg/m² |
| 12 years | 17.8 kg/m² | 18.1 kg/m² |
| 13 years | 18.4 kg/m² | 18.7 kg/m² |
| 14 years | 19.1 kg/m² | 19.3 kg/m² |
| 15 years | 19.8 kg/m² | 19.9 kg/m² |
| 16 years | 20.5 kg/m² | 20.4 kg/m² |
| 17 years | 21.2 kg/m² | 20.9 kg/m² |
| 18 years | 21.9 kg/m² | 21.3 kg/m² |
| 19 years | 22.5 kg/m² | 21.5 kg/m² |
| 20 years | 23.0 kg/m² | 21.7 kg/m² |
The reference values come from the CDC 2000 growth charts, published by the US Centers for Disease Control and Prevention. The CDC publishes them as LMS parameters, which are the official way to describe a growth distribution that is skewed rather than normally distributed. From the three parameters:
M is the median (the 50th percentile value), S is the coefficient of variation and L is the skewness power that bends the distribution into the right shape. The percentile is then the standard normal cumulative distribution at z: percentile = Φ(z) × 100.
Age is interpolated linearly between the published half-month rows, then rounded to the nearest half month. Interpolation in the middle of a 0.5-month gap introduces far less error than the measurement error of a home height or weight reading, which is typically 0.5–1 cm and 0.1–0.2 kg.
| Age | Correct reference | Why |
|---|---|---|
| 0–2 years | WHO growth standards | CDC and the AAP recommend WHO charts for under-2s because they describe how healthy, breastfed infants grow rather than how a mixed US sample grew. |
| 2–20 years | CDC 2000 growth charts | The reference used on this page, and the one US pediatric offices plot against past age 2. |
Mixing the two produces a visible step at age 2, which is exactly the artefact the CDC warns about. If your child is close to that boundary, keep every measurement on the same chart.
The CDC defines a healthy weight for children and teens as a BMI between the 5th and under the 85th percentile for age and sex. Below the 5th is underweight, 85th to under the 95th is overweight, and 95th or above is obesity.
Because body composition changes with age. A BMI of 19 is unremarkable in a 15-year-old and below the 5th percentile in a 6-year-old. Children grow at different rates, so BMI has to be read against age and sex — that is the whole point of the percentile.
The CDC classifies a BMI at or above 120% of the 95th percentile for age and sex (or a BMI of 35 or more) as severe obesity. The calculator works this threshold out from the same LMS data and flags it.
No. CDC and the American Academy of Pediatrics recommend the WHO growth standards for children under 2, not the CDC 2000 charts. The calculator tells you when the age entered falls in that range.
The arithmetic is exact: it applies the CDC's published LMS parameters and the official z-score to percentile conversion. The limiting factor is the measurement — a home height reading is typically within 0.5–1 cm, which moves the percentile by a few points near the middle of the distribution and more at the extremes.