I have large calves, and very few boots will fit me. I tried on a pair at a brick and mortar store, but the only sizes available were sz6 and sz10. I wear a sz8. So I turned to Amazon. My size was in stock, so I ordered a sz8. The shaft fits my calves! I will say that the footbed portion is just a little too large. A thick pair of socks solved this problem. As a resident of the Pacific Northwest I frequently need to wear waterproof shoes, and very seldom can I find boots that fit. So far, so good. One CAUTION: Always wear socks with rubber boots to avoid blisters. These are no exception.