Head circumference for girls at birth
At birth, the median head circumference for girls on the WHO Child Growth Standards is 33.9 cm (13.3 in): half of girls this age measure less and half more. The middle half of girls, from the 25th to the 75th percentile, falls between 33.1 and 34.7 cm, a spread of 1.6 cm. The outer lines of the chart, the 2nd and 98th percentiles, sit at 31.5 and 36.2 cm.
By 1 month it reaches 36.5 cm.
For boys at birth the median is 34.5 cm, 0.6 cm more than for girls, which is why the charts are drawn separately by sex.
On the older CDC 2000 infant charts, which some clinics and websites still use before age 2, the median at birth is 34.7 cm. A girl exactly on the WHO median would read as about the 30th percentile there, one reason two charts can give different answers for the same head circumference.
Reading the table: a girl at birth who measures 34.5 cm is at about the 70th percentile, meaning that out of 100 girls this age, about 70 measure less.
Percentiles at birth
Download CSV (all ages)| Percentile | z-score | Metric | Imperial |
|---|---|---|---|
| 2nd | −2.00 | 31.5 cm | 12.4 in |
| 5th | −1.64 | 31.9 cm | 12.6 in |
| 10th | −1.28 | 32.4 cm | 12.7 in |
| 25th | −0.67 | 33.1 cm | 13.0 in |
| 50th (median) | 0.00 | 33.9 cm | 13.3 in |
| 75th | +0.67 | 34.7 cm | 13.7 in |
| 90th | +1.28 | 35.4 cm | 13.9 in |
| 95th | +1.64 | 35.8 cm | 14.1 in |
| 98th | +2.00 | 36.2 cm | 14.3 in |
WHO charts label z = ±2 as the 2nd and 98th percentiles (exactly 2.3rd and 97.7th), the cutoffs CDC recommends on WHO charts. Values computed with the LMS method from the published tables (retrieved 2026-10-05).