I used the measuring tool and my head measured at 22.5", which is right at the cut off mark for the small size until you need the large size. So, I was a bit nervous getting the small. But, I got the small anyways and it fits exactly how I wanted it to. It is not too tight or have those high areas at the dome that look ridiculous. It fits comfortable snug to my head and has an adjustable strap so it can be further customized to fit. I just got the hat today, but I am going to wear it out and about and see how many compliments I get on it. I recommend to buy the hat if you are in the market of purchasing one.
I included 2 photos, one is of the burgundy hat, and the other is with me wearing the hat and Franklin, my dog, checking it out....awe s'cute.