To figure out your hat size, measure your head with a tape measure about a half-inch above your eyebrows where your hat will rest. If you don't have a tape measure, use a string and measure it against a ruler.
If you are unsure or between sizes, buy the larger size.
||21 5/8 - 22 3/4
||22 3/4 - 23 7/8
||23 7/8 - 25