Head circumference for girls at 3 years
At 3 years, the median head circumference for girls on the CDC 2000 growth charts is 48.6 cm (19.1 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 47.6 and 49.7 cm, a spread of 2.1 cm. The outer lines of the chart, the 3rd and 97th percentiles, sit at 45.6 and 51.4 cm.
Since 2 years, the median has risen by 1.2 cm over 1 year.
For boys at 3 years the median is 49.7 cm, 1.1 cm more than for girls, which is why the charts are drawn separately by sex.
From 2 years, head circumference is read on the CDC 2000 infant charts, which run to 36 months; CDC draws the 3rd to the 97th percentile.
Reading the table: a girl at 3 years who measures 49.5 cm is at about the 71st percentile, meaning that out of 100 girls this age, about 71 measure less.
Percentiles at 3 years
Download CSV (all ages)| Percentile | z-score | Metric | Imperial |
|---|---|---|---|
| 3rd | −1.88 | 45.6 cm | 17.9 in |
| 5th | −1.64 | 46.0 cm | 18.1 in |
| 10th | −1.28 | 46.6 cm | 18.3 in |
| 25th | −0.67 | 47.6 cm | 18.7 in |
| 50th (median) | 0.00 | 48.6 cm | 19.1 in |
| 75th | +0.67 | 49.7 cm | 19.6 in |
| 90th | +1.28 | 50.6 cm | 19.9 in |
| 95th | +1.64 | 51.1 cm | 20.1 in |
| 97th | +1.88 | 51.4 cm | 20.3 in |
CDC 2000 charts draw the 3rd to the 97th percentile. Values computed with the LMS method from the published tables (retrieved 2026-10-05).