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Head circumference chart for boys

WHO and CDC head circumference percentiles for boys. Enter your son’s measurement to see his exact percentile.

Head circumference percentile calculator

Sex

Enter the head circumference to see the percentile.

Data: WHO Child Growth Standards (0 to 24 months) and CDC growth charts (24 to 36 months).

Boys head circumference percentiles

Boys head circumference percentiles
Age (months)3rd10th50th90th97th
0 32.1 cm32.8 cm34.5 cm36.1 cm36.9 cm
1 35.1 cm35.8 cm37.3 cm38.8 cm39.5 cm
2 36.9 cm37.6 cm39.1 cm40.6 cm41.3 cm
3 38.3 cm39 cm40.5 cm42 cm42.7 cm
4 39.4 cm40.1 cm41.6 cm43.2 cm43.9 cm
5 40.3 cm41 cm42.6 cm44.1 cm44.8 cm
6 41 cm41.8 cm43.3 cm44.9 cm45.6 cm
7 41.7 cm42.4 cm44 cm45.6 cm46.3 cm
8 42.2 cm42.9 cm44.5 cm46.1 cm46.9 cm
9 42.6 cm43.4 cm45 cm46.6 cm47.4 cm
10 43 cm43.8 cm45.4 cm47 cm47.8 cm
11 43.4 cm44.1 cm45.8 cm47.4 cm48.2 cm
12 43.6 cm44.4 cm46.1 cm47.7 cm48.5 cm
15 44.3 cm45.1 cm46.8 cm48.5 cm49.3 cm
18 44.9 cm45.7 cm47.4 cm49.1 cm49.9 cm
21 45.3 cm46.1 cm47.8 cm49.6 cm50.4 cm
24 45.7 cm46.5 cm48.3 cm50 cm50.8 cm
30.5 46.3 cm47.3 cm49.3 cm51.2 cm52.1 cm
36 46.4 cm47.5 cm49.7 cm51.7 cm52.6 cm

Average head circumference for baby boys

  • Birth: 34.5 cm (13.6 in)
  • 3 months: 40.5 cm (16.0 in)
  • 6 months: 43.3 cm (17.1 in)
  • 12 months: 46.1 cm (18.1 in)
  • 24 months: 48.3 cm (19.0 in)
  • 36 months: 49.7 cm (19.6 in)

How to measure your head

  1. 1 Use a soft tape measure, or a string and a ruler.
  2. 2 Wrap it around your head where the hat will sit: about 1 cm (⅜ in) above your ears and across the middle of your forehead.
  3. 3 Keep the tape level and snug, not tight. Do not pull it in.
  4. 4 Read the number where the tape overlaps. Measure two or three times and use the largest value.
  5. 5 Type the number into the calculator, or find it in the chart.
How to measure

Frequently asked questions

What is a normal head size for a 6 month old boy?

About 40.9 to 45.8 cm (16.1 to 18.0 in), with a median of 43.3 cm.

What is a normal head size for a 1 year old boy?

About 43.5 to 48.6 cm (17.1 to 19.1 in), with a median of 46.1 cm.

Is a big head normal in baby boys?

Often, yes. Head size runs in families, and many babies with a head above the 90th percentile have a parent with a large head. A doctor looks at the growth curve over time.

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