I am an 8.5-9 (usually a 9) so I went with a 9. This is a very comfortable boot and fits perfectly. It is very snug, which I actually like. When I say snug, I don't mean tight, it just feels "cozy" around your entire foot. If you are interested in putting your own special insole into it you will have to remove the current insole which aren't considered removable, but if you pull hard enough you can remove them. I have problems with ball of foot pain and general foot tenderness and all I have to do with these is add one of those little ball of foot gel pads and these are good to go because they already do have a decent amount in the insole that they come with. I am very glad I bought these as my feet are VERY picky and these boots are actually comfortable and seem true to size.