Average height for a 8-year-old boy
At exactly 8 years old, the median boy in the US is 4'2½" (127.9 cm) tall, according to the CDC growth charts. Half of 8-year-old boys are between 4'1" and 4'4", and about 9 in 10 fall between 3'10½" and 4'6".
Height percentiles for 8-year-old boys
CDC 2000 stature-for-age chart, at 8 years 0 months.
| Percentile | Height | cm | in |
|---|---|---|---|
| 3rd | 3'10" | 117.3 | 46.2 |
| 5th | 3'10½" | 118.6 | 46.7 |
| 10th | 3'11½" | 120.6 | 47.5 |
| 25th | 4'1" | 124.0 | 48.8 |
| 50th (median) | 4'2½" | 127.9 | 50.3 |
| 75th | 4'4" | 131.8 | 51.9 |
| 90th | 4'5½" | 135.4 | 53.3 |
| 95th | 4'6" | 137.5 | 54.2 |
| 97th | 4'6½" | 139.0 | 54.7 |
What’s typical at 8 for boys
Between 8 and 9, the median boy grows about 2 in (5.6 cm) — from 4'2½" to 4'4½".
A median 8-year-old boy has reached about 72% of the CDC's median adult height for men (5'9½"), so roughly 19½ in (49.0 cm) of growth is still typical from here.
This is the steady stretch of childhood: growth runs at a fairly even pace and most boys track along the same percentile line year after year. Puberty, and the growth spurt that comes with it, is still years away — boys typically start between 9 and 14.
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 8-year-old boy be as an adult?
Height at 8 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.