3 month old head circumference
On the WHO growth standard, the average (median) head circumference of a 3-month-old baby boy is 40.5 cm (16.0 in) and of a girl 39.5 cm (15.6 in). The usual range, from the 3rd to the 97th percentile, is 38.3–42.7 cm for boys and 37.2–41.8 cm for girls.
Head circumference percentiles at 3 months (WHO)
The median (50th percentile) is the average head size for this age.
| 3rd | 15th | Median | 85th | 97th | |
|---|---|---|---|---|---|
| Boys (cm) | 38.3 | 39.3 | 40.5 | 41.7 | 42.7 |
| Boys (in) | 15.1 | 15.5 | 16.0 | 16.4 | 16.8 |
| Girls (cm) | 37.2 | 38.3 | 39.5 | 40.8 | 41.8 |
| Girls (in) | 14.7 | 15.1 | 15.6 | 16.1 | 16.5 |
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 3 month old’s head circumference?
WHO percentile for each head circumference, in half centimetres, at exactly 3 months. A few days older or younger shifts it slightly.
| Head | Boy | Girl |
|---|---|---|
| 37.0 cm (14.6 in) | below 1st | 2nd |
| 37.5 cm (14.8 in) | below 1st | 5th |
| 38.0 cm (15.0 in) | 2nd | 11th |
| 38.5 cm (15.2 in) | 4th | 20th |
| 39.0 cm (15.4 in) | 10th | 33rd |
| 39.5 cm (15.6 in) | 20th | 49th |
| 40.0 cm (15.7 in) | 33rd | 65th |
| 40.5 cm (15.9 in) | 50th | 78th |
| 41.0 cm (16.1 in) | 66th | 88th |
| 41.5 cm (16.3 in) | 80th | 95th |
| 42.0 cm (16.5 in) | 90th | 98th |
| 42.5 cm (16.7 in) | 95th | above 99th |
| 43.0 cm (16.9 in) | 98th | above 99th |
Common questions
What is the average head circumference of a 3-month-old baby?
On the WHO growth standard, the average (median) head circumference of a 3-month-old baby boy is 40.5 cm (16.0 in) and of a girl 39.5 cm (15.6 in). The usual range, from the 3rd to the 97th percentile, is 38.3–42.7 cm for boys and 37.2–41.8 cm for girls.
What percentile is a 40 cm head circumference at 3 months?
On the WHO chart, 40 cm (15.7 in) at exactly 3 months is about the 33rd percentile for a boy and the 65th 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 3 months?
Going by the WHO medians, about 1.4 cm for boys and 1.3 cm for girls in the month leading up to 3 months. Head growth is fastest in the first months and slows during the second year.
Is my 3-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: 3 month old baby weight · 3 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 3 completed months. Measure around the widest part of the head, above the eyebrows and ears. For information only; not medical advice.