Boys Head chart in inches for babies 5 month old baby

Head circumference chart for 5-Month-Old boys

What does CDC data show for head circumference in baby boys at 5-Month-Old?

Head circumference percentiles for 5-Month-Old boys

CDC growth chart data shows the following head circumference distribution for baby boys at 5-Month-Old:

• 5th percentile: 15.9 in

• 25th percentile: 16.4 in

• 50th percentile (median): 16.8 in

• 75th percentile: 17.2 in

• 95th percentile: 17.7 in

The percentile values on this page are displayed in inches.

A percentile ranking tells you where your child's measurement falls among baby boys of the same age. The 50th percentile is the statistical midpoint of the population.

Head circumference and development for baby boys

At five months, the rate of head circumference growth is beginning to slow slightly from the rapid newborn pace, though brain development continues intensely.

Tummy time and head shape

Tummy time - supervised play on the stomach - is recommended from birth to reduce the risk of positional plagiocephaly (flat head syndrome). It also strengthens the neck, shoulder, and back muscles needed for later motor development. Start with 2-3 minutes several times a day and build up as the baby becomes stronger. If you notice persistent flattening or asymmetry, mention it at your next health check for early assessment.

Tracking at health checks

Head circumference is plotted on the growth chart at every health check in the first year. Bring your red book or health record to each appointment and ask to see the measurement plotted. The pattern of growth over time is far more informative than any single figure - a baby growing consistently at the 10th percentile is just as healthy as one at the 90th, provided the pattern is stable.

Understanding the fontanelle

The large anterior fontanelle will remain open until approximately 12-18 months as the brain continues to grow. The smaller posterior fontanelle at the back typically closes around two months. Neither requires special protection beyond normal careful handling, but you should avoid pressing on the fontanelle and report any bulging, sunken appearance, or change in tension to your healthcare provider.

Frequently asked questions

What is a normal head circumference for this age?

The percentile table on this page shows the full range of typical head circumferences. All values from the 5th to the 95th percentile are within normal limits. As with all growth measurements, the pattern of growth over time is more informative than any single reading - a baby growing consistently at the 15th percentile is growing normally.

How fast does head circumference grow in the first year?

Head circumference grows approximately 10-12 cm in the first year of life - roughly 2 cm per month in the first 3 months, slowing to about 1 cm per month from 3-6 months, and 0.5 cm per month from 6-12 months. By 12 months, the average head circumference has grown from approximately 34-35 cm at birth to around 46-47 cm.

What is the fontanelle and when does it close?

The fontanelle is the soft spot on the top of a baby's head where the skull bones have not yet fused. There are two fontanelles: the larger anterior (front) fontanelle, which typically closes between 9 and 18 months, and the smaller posterior (back) fontanelle, which usually closes by 2-3 months. Both allow the skull to expand rapidly as the brain grows during the first years of life.

Data sources and methodology

The percentile ranges on this page are drawn from CDC growth chart data from the National Center for Health Statistics and WHO Child Growth Standards (for children under 5). CDC data published May 30, 2000, with 2022 extended BMI tables. Percentiles are modelled using the LMS method (Box-Cox transformation), which accounts for the skewed distribution of measurements at each age. All measurements are given in metric units with imperial equivalents.

Growth charts are screening tools, not diagnostic ones. If you have concerns about your child's measurements, a GP or paediatrician is the right first step.