Understanding the result
- Percentile — where his height falls among boys the same age in the CDC reference. 50th is the middle; 90th means taller than about 90% of peers.
- Z-score — the same information in standard-deviation units. 0 is the median; +1 and −1 are roughly the 84th and 16th percentiles.
- Median for age — the reference midpoint (50th percentile) height for his exact age, shown in cm and ft/in.
One measurement is a snapshot, not a verdict. Pediatricians care most about the pattern over time — a child tracking steadily along their own curve is reassuring even if the percentile itself is high or low.
Which ages are covered?
This quick check uses the CDC 2000 stature-for-age reference for boys, which covers ages 2 to 20 years (standing height). If you enter an age outside that range, the calculator says so honestly instead of inventing a number.
For a boy under 2, height is measured lying down (length) and the right reference is the WHO standard — see our baby height calculator (0–24 months). For the full CDC / WHO / UK-WHO switcher, z-scores, and exact percentiles, use the boys height percentile calculator; to see the curves, open the boys growth chart.