Average adult head circumference
These figures come from ANSUR II, a 2012 survey that measured more than 6,000 US Army personnel with the tape pressed firmly over the hair. The general population varies a little more, but the averages are similar.
- Men: 57.4 cm (22.6 in) on average. Nine in ten men measure between 54.8 and 60.1 cm.
- Women: 56.1 cm (22.1 in) on average. Nine in ten women measure between 53.2 and 59.7 cm.
Average head circumference for babies and children
- Birth: 34.5 cm for boys, 33.9 cm for girls (WHO median).
- 6 months: 43.3 cm for boys, 42.2 cm for girls.
- 12 months: 46.1 cm for boys, 44.9 cm for girls.
- 24 months: 48.3 cm for boys, 47.2 cm for girls.
- 36 months: 49.7 cm for boys, 48.6 cm for girls (CDC median).
Average head size and hat size
An average man’s 57.4 cm head is a fitted 7 ¼, and an average woman’s 56.1 cm head is a 7. Most men wear 7 ⅛ to 7 ⅜: about 7 in 10 fall between 7 and 7 ⅜, and only about 4% measure 7 ⅝ or larger.