Boys head circumference percentiles
| Age (months) | 3rd | 10th | 50th | 90th | 97th |
|---|---|---|---|---|---|
| 0 | 32.1 cm | 32.8 cm | 34.5 cm | 36.1 cm | 36.9 cm |
| 1 | 35.1 cm | 35.8 cm | 37.3 cm | 38.8 cm | 39.5 cm |
| 2 | 36.9 cm | 37.6 cm | 39.1 cm | 40.6 cm | 41.3 cm |
| 3 | 38.3 cm | 39 cm | 40.5 cm | 42 cm | 42.7 cm |
| 4 | 39.4 cm | 40.1 cm | 41.6 cm | 43.2 cm | 43.9 cm |
| 5 | 40.3 cm | 41 cm | 42.6 cm | 44.1 cm | 44.8 cm |
| 6 | 41 cm | 41.8 cm | 43.3 cm | 44.9 cm | 45.6 cm |
| 7 | 41.7 cm | 42.4 cm | 44 cm | 45.6 cm | 46.3 cm |
| 8 | 42.2 cm | 42.9 cm | 44.5 cm | 46.1 cm | 46.9 cm |
| 9 | 42.6 cm | 43.4 cm | 45 cm | 46.6 cm | 47.4 cm |
| 10 | 43 cm | 43.8 cm | 45.4 cm | 47 cm | 47.8 cm |
| 11 | 43.4 cm | 44.1 cm | 45.8 cm | 47.4 cm | 48.2 cm |
| 12 | 43.6 cm | 44.4 cm | 46.1 cm | 47.7 cm | 48.5 cm |
| 15 | 44.3 cm | 45.1 cm | 46.8 cm | 48.5 cm | 49.3 cm |
| 18 | 44.9 cm | 45.7 cm | 47.4 cm | 49.1 cm | 49.9 cm |
| 21 | 45.3 cm | 46.1 cm | 47.8 cm | 49.6 cm | 50.4 cm |
| 24 | 45.7 cm | 46.5 cm | 48.3 cm | 50 cm | 50.8 cm |
| 30.5 | 46.3 cm | 47.3 cm | 49.3 cm | 51.2 cm | 52.1 cm |
| 36 | 46.4 cm | 47.5 cm | 49.7 cm | 51.7 cm | 52.6 cm |
Average head circumference for baby boys
- Birth: 34.5 cm (13.6 in)
- 3 months: 40.5 cm (16.0 in)
- 6 months: 43.3 cm (17.1 in)
- 12 months: 46.1 cm (18.1 in)
- 24 months: 48.3 cm (19.0 in)
- 36 months: 49.7 cm (19.6 in)