How to measure your size:
When purchasing a new hat, it is important to be as accurate as possible with your head measurements to prevent getting a hat that is under or over-sized. You will need to measure your head using a clothes tape, or you can improvise using a piece of string and a ruler.
To take your head measurement, place the string or tape around your head around where the hat will sit. This should roughly be about 1/8" above your ear, across the mid-forehead, and completely circling your head. Hold the tape firmly, but not too tightly. If your measurement falls between sizes, choose the next largest size.