American vs. European sizing

[Kaleponi Craig]

I was wondering if anyone knows how to calculate American sizing when you see the European size on a hat. On Ebay, you often see a vintage Borsalino with a size of 4 1/2 or something like that. Any ideas what this means in the real world??

Thanks...KC

 

[SHARPETOYS]

This should help you.

http://www.hatlife.com/headsize.php