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Head circumference chart

Percentile charts for boys and girls from birth to 36 months. Use the calculator for an 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).

Head circumference chart for boys

Values in centimetres. Birth to 24 months from the WHO Child Growth Standards; 30 and 36 months from the CDC growth charts.

Head circumference chart for boys
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

Head circumference chart for girls

Head circumference chart for girls
Age (months)3rd10th50th90th97th
0 31.7 cm32.4 cm33.9 cm35.4 cm36.1 cm
1 34.3 cm35 cm36.5 cm38 cm38.8 cm
2 36 cm36.7 cm38.3 cm39.8 cm40.5 cm
3 37.2 cm37.9 cm39.5 cm41.1 cm41.9 cm
4 38.2 cm39 cm40.6 cm42.2 cm43 cm
5 39 cm39.8 cm41.5 cm43.1 cm43.9 cm
6 39.7 cm40.5 cm42.2 cm43.9 cm44.6 cm
7 40.4 cm41.1 cm42.8 cm44.5 cm45.3 cm
8 40.9 cm41.7 cm43.4 cm45.1 cm45.9 cm
9 41.3 cm42.1 cm43.8 cm45.5 cm46.3 cm
10 41.7 cm42.5 cm44.2 cm46 cm46.8 cm
11 42 cm42.9 cm44.6 cm46.3 cm47.1 cm
12 42.3 cm43.2 cm44.9 cm46.6 cm47.5 cm
15 43.1 cm43.9 cm45.7 cm47.4 cm48.2 cm
18 43.6 cm44.5 cm46.2 cm48 cm48.8 cm
21 44.1 cm45 cm46.7 cm48.5 cm49.4 cm
24 44.6 cm45.4 cm47.2 cm49 cm49.8 cm
30.5 45.3 cm46.3 cm48.2 cm50 cm50.9 cm
36 45.6 cm46.6 cm48.6 cm50.6 cm51.4 cm

How to read the chart

Find the age in months, then compare the measurement with the percentile columns. A value halfway between the 10th and 50th columns is roughly the 25th to 30th percentile. The calculator above gives the exact figure.

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 the average head circumference at 12 months?

The WHO median at 12 months is 46.1 cm (18.1 in) for boys and 44.9 cm (17.7 in) for girls.

How much does a baby’s head grow in the first year?

About 11 to 12 cm. The WHO median for boys grows from 34.5 cm at birth to 46.1 cm at 12 months.

Why do boys and girls have separate charts?

Boys’ heads are slightly larger on average, by about 1 cm at 12 months, so separate charts give a fairer comparison.

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