There is more than one store at the nearby mall that sells pro-fitted baseball caps. I went to one to get an idea of what size I'd need, tried out two different sizes that both fit to the point where I couldn't tell any difference. At another store, the exact same two sizes of the same cap from the same brand -- one was too small and the other was too big! WTF?!?!?!? The third store had the cap I wanted in the size I needed. Wasn't a perfect fit but wasn't too big either, but it was good enough.