WHO growth standards · birth to 5 years
Baby Boy Head Circumference Chart
The average baby boy's head measures about 34.5 cm (13.6 in) around at birth, 43.3 cm at 6 months, 46.1 cm at 1 year and 48.2 cm at 2 years, according to the WHO growth standards.
Educational content only, not medical advice. Always talk to your doctor or health visitor about your child. One measurement says very little. Doctors look at the curve over several visits.
Head circumference chart for boys by month
Values at the 3rd, 15th, 50th (median), 85th and 97th percentiles, calculated from the WHO LMS tables. Switch between cm and in.
| Age | 3rd | 15th | 50th | 85th | 97th |
|---|---|---|---|---|---|
| Birth | 32.1 | 33.1 | 34.5 | 35.8 | 36.9 |
| 1 month | 35.0 | 36.0 | 37.2 | 38.4 | 39.4 |
| 2 months | 36.9 | 37.9 | 39.1 | 40.3 | 41.3 |
| 3 months | 38.3 | 39.3 | 40.5 | 41.7 | 42.7 |
| 4 months | 39.4 | 40.4 | 41.6 | 42.9 | 43.9 |
| 5 months | 40.3 | 41.3 | 42.6 | 43.8 | 44.8 |
| 6 months | 41.0 | 42.1 | 43.3 | 44.6 | 45.6 |
| 7 months | 41.7 | 42.7 | 44.0 | 45.3 | 46.3 |
| 8 months | 42.2 | 43.2 | 44.5 | 45.8 | 46.9 |
| 9 months | 42.6 | 43.7 | 45.0 | 46.3 | 47.4 |
| 10 months | 43.0 | 44.1 | 45.4 | 46.7 | 47.8 |
| 11 months | 43.4 | 44.4 | 45.8 | 47.1 | 48.2 |
| 12 months | 43.6 | 44.7 | 46.1 | 47.4 | 48.5 |
| 13 months | 43.9 | 45.0 | 46.3 | 47.7 | 48.8 |
| 14 months | 44.1 | 45.2 | 46.6 | 47.9 | 49.0 |
| 15 months | 44.4 | 45.5 | 46.8 | 48.2 | 49.3 |
| 16 months | 44.5 | 45.6 | 47.0 | 48.4 | 49.5 |
| 17 months | 44.7 | 45.8 | 47.2 | 48.6 | 49.7 |
| 18 months | 44.9 | 46.0 | 47.4 | 48.7 | 49.9 |
| 19 months | 45.0 | 46.2 | 47.5 | 48.9 | 50.0 |
| 20 months | 45.2 | 46.3 | 47.7 | 49.1 | 50.2 |
| 21 months | 45.3 | 46.4 | 47.8 | 49.2 | 50.4 |
| 22 months | 45.4 | 46.6 | 48.0 | 49.4 | 50.5 |
| 23 months | 45.6 | 46.7 | 48.1 | 49.5 | 50.7 |
| 2 years | 45.7 | 46.8 | 48.2 | 49.7 | 50.8 |
| 2 years 3 months | 46.0 | 47.2 | 48.6 | 50.0 | 51.2 |
| 2 years 6 months | 46.3 | 47.5 | 48.9 | 50.4 | 51.6 |
| 2 years 9 months | 46.6 | 47.8 | 49.2 | 50.7 | 51.9 |
| 3 years | 46.8 | 48.0 | 49.5 | 50.9 | 52.1 |
| 3 years 3 months | 47.0 | 48.2 | 49.7 | 51.2 | 52.4 |
| 3 years 6 months | 47.2 | 48.4 | 49.9 | 51.4 | 52.6 |
| 3 years 9 months | 47.3 | 48.5 | 50.1 | 51.6 | 52.8 |
| 4 years | 47.5 | 48.7 | 50.2 | 51.7 | 53.0 |
| 4 years 3 months | 47.6 | 48.8 | 50.4 | 51.9 | 53.1 |
| 4 years 6 months | 47.7 | 49.0 | 50.5 | 52.0 | 53.3 |
| 4 years 9 months | 47.8 | 49.1 | 50.6 | 52.2 | 53.4 |
| 5 years | 47.9 | 49.2 | 50.7 | 52.3 | 53.5 |
| Age | 3rd | 15th | 50th | 85th | 97th |
|---|---|---|---|---|---|
| Birth | 12.6 | 13.0 | 13.6 | 14.1 | 14.5 |
| 1 month | 13.8 | 14.2 | 14.7 | 15.1 | 15.5 |
| 2 months | 14.5 | 14.9 | 15.4 | 15.9 | 16.3 |
| 3 months | 15.1 | 15.5 | 15.9 | 16.4 | 16.8 |
| 4 months | 15.5 | 15.9 | 16.4 | 16.9 | 17.3 |
| 5 months | 15.9 | 16.3 | 16.8 | 17.2 | 17.6 |
| 6 months | 16.2 | 16.6 | 17.1 | 17.6 | 18.0 |
| 7 months | 16.4 | 16.8 | 17.3 | 17.8 | 18.2 |
| 8 months | 16.6 | 17.0 | 17.5 | 18.0 | 18.5 |
| 9 months | 16.8 | 17.2 | 17.7 | 18.2 | 18.6 |
| 10 months | 16.9 | 17.4 | 17.9 | 18.4 | 18.8 |
| 11 months | 17.1 | 17.5 | 18.0 | 18.5 | 19.0 |
| 12 months | 17.2 | 17.6 | 18.1 | 18.7 | 19.1 |
| 13 months | 17.3 | 17.7 | 18.2 | 18.8 | 19.2 |
| 14 months | 17.4 | 17.8 | 18.3 | 18.9 | 19.3 |
| 15 months | 17.5 | 17.9 | 18.4 | 19.0 | 19.4 |
| 16 months | 17.5 | 18.0 | 18.5 | 19.0 | 19.5 |
| 17 months | 17.6 | 18.0 | 18.6 | 19.1 | 19.6 |
| 18 months | 17.7 | 18.1 | 18.7 | 19.2 | 19.6 |
| 19 months | 17.7 | 18.2 | 18.7 | 19.3 | 19.7 |
| 20 months | 17.8 | 18.2 | 18.8 | 19.3 | 19.8 |
| 21 months | 17.8 | 18.3 | 18.8 | 19.4 | 19.8 |
| 22 months | 17.9 | 18.3 | 18.9 | 19.4 | 19.9 |
| 23 months | 17.9 | 18.4 | 18.9 | 19.5 | 19.9 |
| 2 years | 18.0 | 18.4 | 19.0 | 19.6 | 20.0 |
| 2 years 3 months | 18.1 | 18.6 | 19.1 | 19.7 | 20.2 |
| 2 years 6 months | 18.2 | 18.7 | 19.3 | 19.8 | 20.3 |
| 2 years 9 months | 18.3 | 18.8 | 19.4 | 19.9 | 20.4 |
| 3 years | 18.4 | 18.9 | 19.5 | 20.1 | 20.5 |
| 3 years 3 months | 18.5 | 19.0 | 19.6 | 20.1 | 20.6 |
| 3 years 6 months | 18.6 | 19.0 | 19.6 | 20.2 | 20.7 |
| 3 years 9 months | 18.6 | 19.1 | 19.7 | 20.3 | 20.8 |
| 4 years | 18.7 | 19.2 | 19.8 | 20.4 | 20.9 |
| 4 years 3 months | 18.7 | 19.2 | 19.8 | 20.4 | 20.9 |
| 4 years 6 months | 18.8 | 19.3 | 19.9 | 20.5 | 21.0 |
| 4 years 9 months | 18.8 | 19.3 | 19.9 | 20.5 | 21.0 |
| 5 years | 18.9 | 19.4 | 20.0 | 20.6 | 21.1 |
How to read this chart
Find your boy's age on the bottom, then the measurement on the side. Where the two meet tells you his percentile. On the 25th percentile, 25 out of 100 healthy boys the same age measure less and 75 measure more. That is completely normal.
- Follow the curve. A boy who keeps to roughly the same line from visit to visit is usually growing well, whatever the line.
- Watch for big jumps. Crossing two or more major percentile lines up or down is worth a chat with your doctor.
- Look at the whole picture. Weight, length and head size are read together, alongside how he is feeding, sleeping and developing.
How to measure at home
Head circumference is measured around the widest part of the head, just above the eyebrows and ears, with a soft tape that does not stretch. Read our full guide on how to measure your baby at home.
Other WHO growth charts
- Baby Girl Weight Chart
- Baby Boy Weight Chart
- Baby Girl Height and Length Chart
- Baby Boy Height and Length Chart
- Baby Girl Head Circumference Chart
- Average baby weight by month
- Average baby length by month
Frequently asked questions
What is a normal head circumference for a baby boy?
Anything between the 3rd and 97th percentile on the WHO chart is within the normal range. What matters most is that his measurements follow a similar curve over time.
Is the 50th percentile the goal?
No. The 50th percentile is the middle, not a target. A boy on the 10th or the 90th percentile who stays on that curve is usually growing well.
Which chart should I use for my baby boy?
Most countries use the WHO Child Growth Standards for children from birth to 5 years, including the UK and the US CDC for children under 2. This chart uses those WHO tables.
When should I talk to a doctor about my boy's head circumference?
Talk to your doctor or health visitor if a measurement falls below the 3rd or above the 97th percentile, if it crosses two or more major percentile lines, or any time you are worried.
