Average height for a 9-year-old boy
At exactly 9 years old, the median boy in the US is 4'4½" (133.5 cm) tall, according to the CDC growth charts. Half of 9-year-old boys are between 4'3" and 4'6", and about 9 in 10 fall between 4'0½" and 4'8½".
Height percentiles for 9-year-old boys
CDC 2000 stature-for-age chart, at 9 years 0 months.
| Percentile | Height | cm | in |
|---|---|---|---|
| 3rd | 4'0" | 122.2 | 48.1 |
| 5th | 4'0½" | 123.6 | 48.7 |
| 10th | 4'1½" | 125.7 | 49.5 |
| 25th | 4'3" | 129.4 | 50.9 |
| 50th (median) | 4'4½" | 133.5 | 52.6 |
| 75th | 4'6" | 137.7 | 54.2 |
| 90th | 4'7½" | 141.5 | 55.7 |
| 95th | 4'8½" | 143.9 | 56.6 |
| 97th | 4'9" | 145.4 | 57.2 |
What’s typical at 9 for boys
Between 9 and 10, the median boy grows about 2 in (5.1 cm) — from 4'4½" to 4'6½".
A median 9-year-old boy has reached about 75% of the CDC's median adult height for men (5'9½"), so roughly 17 in (43.3 cm) of growth is still typical from here.
Growth is still at the steady childhood pace for most boys. Puberty typically begins between 9 and 14, so a few boys this age are starting to speed up while most are not; an early or late start here says very little about final height.
How to read a percentile
A percentile compares a child with others of the same age and sex on the CDC 2000 growth charts — the same L, M and S values a pediatrician’s chart is drawn from, and where every number on this page comes from. The 50th percentile is the median: half of boys that age are shorter and half are taller. The 5th and 95th bracket the middle 90%.
Pediatricians care less about the number than the line. A child who stays near the same percentile year after year is growing normally, whatever that percentile is — a steady 15th is healthier than a 60th that has just dropped from the 90th. Crossing two of the major lines, or sitting below the 3rd, is the usual cue to have a pediatrician take a look. None of this is medical advice.
How tall will a 9-year-old boy be as an adult?
Height at 9 is one input. The calculator combines it with both parents’ heights and puberty timing to give the range adult height will most likely land in — free, no account.
Try the height calculatorThe MaxHeight app shows the number inside that range and sharpens it as you log — free to download on the App Store.
Source: CDC 2000 growth charts, stature-for-age LMS parameters (statage.csv). Adult figures: NHANES 2015–2018. MaxHeight is not affiliated with or endorsed by the CDC.