most ski boots fit large. the whole system of 27.5 = 9.5 is total bullshit. I wear a size 9.5 street shoe and would be swimming in a 27.5 boot. its a good rule of thumb to size down at least 11/2 if not 3 shoe sizes to get a good solid fit. I would say someone with a size 11 foot could fit into these especially with how roomy the spks are. peace