I'm a Texan born and raised, cold to me is 65F or less. I've spent many winters aching and miserable because I work outdoors for extended hours, so I decided to invest in boots that are evidently intended for Siberia. I'm proud to say I finally was able to enjoy being in the 20s all day. I also had superior traction, and they were so comfortable I felt like I had on oversized house slippers. I wear an 8 USA in Mizuno Women, a 6 UK in Dr Martens, and 7.5 in Frye. You can print a sizing chart from the Sorel site and trace your foot to size, I drew an 8.5- but based on others comments I ordered a 7.5. My heel slips just a little, but I have room for a thicker sock. I wouldn't go any smaller, I think larger would have been too big since I normally wear a wool Med Cushion sock. There is a thick removeable insulate bootie inside that even wicks moisture away from your body. The stripe is reflective, a big safety bonus that I didn't see on any others. My only complaint is that they don't have a line of clothing too.