I bought medium size however It is a bit large for a person who naturally wears a perfect size 10. The boot area on the top of the foot has way too much room. I put adr schols insert in it and i believe i still need to wear a thick sock or a thicker gel pad.  a gel pad is good since the boot is too hard on your heels. its a little long and i have at least 2 inches from my toe to the tip of the boot. however im afraid to swap it out for a size 9 which may rub so im gonna work with these and wear thick socks and thick insoles and hope that it works. the top part for your leg is made for normal legs  not muscular or wide calfs. it also gets hot since its not real leather so my legs was sweating a bit.