I have a small head and so I say somewhat large for me! I have to add a little more Velcro to tighten but that is no trouble since my tennis partners Mum is doing it for me. Its lovely and light weight. Coverage is amazing and it doesn't get in the way of your tennis. Since I don't like looking like a "Handmaiden" I flip the edge of the brim up. Still perfect coverage. I have long hair so I put in a pony tail and thread thru the back of the hat between the tie. Works really well. Very pleased.