4 month old head circumference
On the WHO growth standard, the average (median) head circumference of a 4-month-old baby boy is 41.6 cm (16.4 in) and of a girl 40.6 cm (16.0 in). The usual range, from the 3rd to the 97th percentile, is 39.4–43.9 cm for boys and 38.2–42.9 cm for girls.
Head circumference percentiles at 4 months (WHO)
The median (50th percentile) is the average head size for this age.
| 3rd | 15th | Median | 85th | 97th | |
|---|---|---|---|---|---|
| Boys (cm) | 39.4 | 40.4 | 41.6 | 42.9 | 43.9 |
| Boys (in) | 15.5 | 15.9 | 16.4 | 16.9 | 17.3 |
| Girls (cm) | 38.2 | 39.3 | 40.6 | 41.9 | 42.9 |
| Girls (in) | 15.1 | 15.5 | 16.0 | 16.5 | 16.9 |
Check your baby’s head circumference percentile
Enter the exact date of birth for a precise result, or use the centimetre table below.
Enter a date of birth and at least one measurement to see the percentile.
What percentile is my 4 month old’s head circumference?
WHO percentile for each head circumference, in half centimetres, at exactly 4 months. A few days older or younger shifts it slightly.
| Head | Boy | Girl |
|---|---|---|
| 38.0 cm (15.0 in) | below 1st | 2nd |
| 38.5 cm (15.2 in) | below 1st | 5th |
| 39.0 cm (15.4 in) | 1st | 10th |
| 39.5 cm (15.6 in) | 4th | 19th |
| 40.0 cm (15.7 in) | 9th | 32nd |
| 40.5 cm (15.9 in) | 17th | 47th |
| 41.0 cm (16.1 in) | 30th | 63rd |
| 41.5 cm (16.3 in) | 46th | 77th |
| 42.0 cm (16.5 in) | 62nd | 87th |
| 42.5 cm (16.7 in) | 77th | 94th |
| 43.0 cm (16.9 in) | 87th | 97th |
| 43.5 cm (17.1 in) | 94th | above 99th |
| 44.0 cm (17.3 in) | 98th | above 99th |
Common questions
What is the average head circumference of a 4-month-old baby?
On the WHO growth standard, the average (median) head circumference of a 4-month-old baby boy is 41.6 cm (16.4 in) and of a girl 40.6 cm (16.0 in). The usual range, from the 3rd to the 97th percentile, is 39.4–43.9 cm for boys and 38.2–42.9 cm for girls.
What percentile is a 41 cm head circumference at 4 months?
On the WHO chart, 41 cm (16.1 in) at exactly 4 months is about the 30th percentile for a boy and the 63rd percentile for a girl. The table on this page gives the percentile for every half centimetre in the usual range.
How much does head circumference grow around 4 months?
Going by the WHO medians, about 1.1 cm for boys and 1.0 cm for girls in the month leading up to 4 months. Head growth is fastest in the first months and slows during the second year.
Is my 4-month-old's head too big or too small?
A head circumference between the 3rd and the 97th percentile is within the usual range, and head size often runs in families. Pediatricians look most at the trend: talk to yours if the measurement is below the 3rd or above the 97th percentile, or if the curve crosses two of the main percentile lines between visits.
Also: 4 month old baby weight · 4 month old baby length · head circumference chart by month · about head circumference
Source: WHO Child Growth Standards, head circumference-for-age, percentiles computed from the WHO LMS tables at 4 completed months. Measure around the widest part of the head, above the eyebrows and ears. For information only; not medical advice.