Newborn head circumference chart by week
WHO head circumference percentiles for newborn girls and boys at every week from birth to 13 weeks, in cm with inches for the median. For older babies, see the head circumference chart by month.
Key numbers
- At birth, the WHO median head circumference is 33.9 cm (13.3 in) for girls and 34.5 cm (13.6 in) for boys.
- At 6 weeks, the median is 37.3 cm (14.7 in) for girls and 38.1 cm (15.0 in) for boys.
- At 13 weeks (about 3 months), the median is 39.5 cm (15.6 in) for girls and 40.5 cm (15.9 in) for boys.
- In the first 13 weeks the median head grows about 5.6 cm for girls and 6.0 cm for boys, roughly half a centimeter a week, which is faster than at any later age.
Girls: head circumference by week (WHO)
Values in cm at each percentile. Median also in inches.
| Age | 3th | 15th | Median | 85th | 97th | Median (in) |
|---|---|---|---|---|---|---|
| Birth | 31.7 | 32.7 | 33.9 | 35.1 | 36.1 | 13.3 |
| 1 week | 32.4 | 33.3 | 34.6 | 35.8 | 36.7 | 13.6 |
| 2 weeks | 33.1 | 34.0 | 35.2 | 36.4 | 37.4 | 13.9 |
| 3 weeks | 33.7 | 34.6 | 35.8 | 37.0 | 38.0 | 14.1 |
| 4 weeks | 34.2 | 35.2 | 36.4 | 37.6 | 38.6 | 14.3 |
| 5 weeks | 34.6 | 35.6 | 36.8 | 38.1 | 39.1 | 14.5 |
| 6 weeks | 35.0 | 36.0 | 37.3 | 38.5 | 39.5 | 14.7 |
| 7 weeks | 35.4 | 36.4 | 37.7 | 38.9 | 39.9 | 14.8 |
| 8 weeks | 35.7 | 36.8 | 38.0 | 39.3 | 40.3 | 15.0 |
| 9 weeks | 36.1 | 37.1 | 38.4 | 39.6 | 40.6 | 15.1 |
| 10 weeks | 36.4 | 37.4 | 38.7 | 39.9 | 41.0 | 15.2 |
| 11 weeks | 36.7 | 37.7 | 39.0 | 40.2 | 41.3 | 15.3 |
| 12 weeks | 36.9 | 38.0 | 39.3 | 40.5 | 41.6 | 15.5 |
| 13 weeks | 37.2 | 38.2 | 39.5 | 40.8 | 41.9 | 15.6 |
Boys: head circumference by week (WHO)
Values in cm at each percentile. Median also in inches.
| Age | 3th | 15th | Median | 85th | 97th | Median (in) |
|---|---|---|---|---|---|---|
| Birth | 32.1 | 33.1 | 34.5 | 35.8 | 36.9 | 13.6 |
| 1 week | 32.9 | 33.9 | 35.2 | 36.4 | 37.5 | 13.8 |
| 2 weeks | 33.7 | 34.7 | 35.9 | 37.1 | 38.1 | 14.1 |
| 3 weeks | 34.3 | 35.3 | 36.5 | 37.7 | 38.7 | 14.4 |
| 4 weeks | 34.9 | 35.9 | 37.1 | 38.3 | 39.3 | 14.6 |
| 5 weeks | 35.4 | 36.4 | 37.6 | 38.8 | 39.8 | 14.8 |
| 6 weeks | 35.9 | 36.8 | 38.1 | 39.3 | 40.3 | 15.0 |
| 7 weeks | 36.3 | 37.3 | 38.5 | 39.7 | 40.7 | 15.2 |
| 8 weeks | 36.7 | 37.7 | 38.9 | 40.1 | 41.1 | 15.3 |
| 9 weeks | 37.0 | 38.0 | 39.2 | 40.5 | 41.4 | 15.4 |
| 10 weeks | 37.4 | 38.4 | 39.6 | 40.8 | 41.8 | 15.6 |
| 11 weeks | 37.7 | 38.7 | 39.9 | 41.1 | 42.1 | 15.7 |
| 12 weeks | 38.0 | 39.0 | 40.2 | 41.4 | 42.4 | 15.8 |
| 13 weeks | 38.3 | 39.3 | 40.5 | 41.7 | 42.7 | 15.9 |
Reading a newborn’s head measurement
Head size in the first months reflects brain growth, which is fastest right after birth. That is why the curve on this chart rises so steeply, and why pediatricians measure the head at every visit.
Measurements in the first days are less reliable: the head is often moulded by birth and the scalp can be swollen. From about the second week, compare each measurement with the one before. A head that keeps to roughly the same percentile is growing as expected; one that climbs or falls across two percentile lines is worth raising with your pediatrician. More in Why head circumference matters.
Check a head measurement
Enter a date of birth and at least one measurement to see the percentile.
Common questions
What is a normal head circumference for a newborn?
On the WHO standard, the 3rd to 97th percentile at birth runs from about 31.7 to 36.1 cm for girls and 32.1 to 36.9 cm for boys.
Why does my newborn’s head measurement change in the first days?
A baby’s head is often moulded by birth and can have swelling of the scalp. Measurements in the first few days can be off by a centimeter or more, so the measurements from later checkups give a clearer picture.
How do I measure my baby’s head circumference?
Use a flexible, non-stretch tape around the widest part of the head, just above the eyebrows and ears and around the back of the head. Take the largest of two or three readings.
When should I talk to the pediatrician?
If a measurement is far outside the chart (roughly below the 2nd or above the 98th percentile), if head growth seems to stop, or if it climbs across percentile lines quickly. Doctors read head size together with development and the parents’ head sizes.
Track head growth over time
Growthling plots each head measurement on the WHO chart with its percentile, next to weight and length. Free to sign up.
Start tracking freeSource: WHO Child Growth Standards, head circumference-for-age expanded tables. Related: newborn weight chart by week. For information only; not medical advice.