My hat size is a 7 3/4.
I hate how most hats nowadays only come in small, medium, and large.
Medium is too small and large is, well, too large. Bastards.
When I was in high school I got a pinstripe suit and wanted a fedora to go with it because fedoras are awesome. Apparently, only two stores in Green Bay stock fedoras, and only in one size. I got the large, and of course, it was too big. Also, the form was kinda goofy. The brim was really more of an Edwardian style (bowl shaped) but it worked in a pinch after a little creative bending.
I found my favorite hat (my boonie) on a fluke at an Army-Navy Surplus store. It was the only one they had and it was in my size!