I typically wear a size 7 or 7.5, and I have large calf muscles.  Based on the reviews, I bought the 7.5 regular calf boots.  They did not work at all!  The shaft was super skinny, and the shoe part was comically big.  I repurchased in a 7 WC, and they fit perfectly.  They actually are wide enough in the shaft that I don't get indentations fin my skin from the zipper--these are the only boots that don't do that to me!  The seller was quick to process my refund as soon as they received the original pair back.  I was very happy with the boots I purchased, and with the ease of the return.