Height Percentile Calculator (CDC & WHO)
Enter your child's sex, age, and height. This calculator automatically uses the WHO standard under 2 years and the CDC standard from 2 to 20 years, and shows the P3-P97 row for that exact age.
Height percentile (CDC standard)
55th percentile
CDC 2000 (2-20y) · z-score +0.12
| Age | P3 | P10 | P25 | P50 | P75 | P90 | P97 |
|---|---|---|---|---|---|---|---|
| 6y 0m (CDC) | 105.9 cm | 108.9 cm | 112.0 cm | 115.4 cm | 118.8 cm | 121.8 cm | 124.8 cm |
In inches: median 45.4"
How the percentile is calculated
Both standards use the LMS method: at every age, a measurement's distribution is summarized by three numbers -- L (a skew-correcting power), M (the median), and S (roughly, the spread). A z-score is worked out from your child's height and those three numbers, then converted to a percentile with the standard normal distribution.
Worked example
A 6-year-old boy at 120cm: the CDC table gives L=1.150, M=115.39cm, S=0.0436 for 72 months. z = ((120/115.39)^1.150 − 1) / (1.150 × 0.0436) = 0.92, which is the 82th percentile.
A 12-month-old girl at exactly the WHO median length, 74.0cm, lands at z = 0, the 50th percentile exactly -- because the median is, by definition, the value at z = 0.
Frequently Asked Questions
Why does this use two different charts?
Under 2 years old, pediatricians use the WHO growth standards, built from breastfed infants across several countries -- the closest thing to a description of how a well-fed baby is supposed to grow. From 2 to 20 years, the standard is the CDC's 2000 growth charts, built from a large US national health survey. The two aren't perfectly continuous at the 24-month handoff -- that's a real, published feature of using both, not an error on this page.
My child is exactly at the 50th percentile -- is that 'best'?
No. The 50th percentile is the median, not a target. A child steadily tracking the 10th percentile, growing along that same curve month after month, is typically just as healthy as one tracking the 90th. What a pediatrician actually watches for is a percentile that crosses two or more major lines in either direction, not distance from the middle.
What's a z-score, and why is it shown next to the percentile?
The z-score is how many standard deviations a measurement is from the median for that age and sex -- the percentile is just the z-score converted to a 0-100 scale. Z-scores are more useful than percentiles at the extremes: the gap between the 1st and 0.1st percentile is enormous in z-score terms but looks tiny on a 0-100 scale.
Can I use this for a premature baby?
Use corrected age (chronological age minus the weeks born early) rather than birth-date age for a baby born before 37 weeks, until about 24 months -- that's standard pediatric practice, and it's built into the baby percentile calculator's optional gestational-age field.
These calculators estimate from published population reference data (the CDC and WHO growth charts) and published rules of thumb -- not a diagnosis, and not a substitute for your pediatrician, who tracks your child's own growth curve over time and knows their history.