In my experience it, it depends on the make of the boot. Hodgeman bantam weights, for instance, are oversized, and it is recommended that you purchase your foot size.Also keep in mind, that most stockingfoots, are sized 9-11, 11-13,13-15, etc, there could be a lot of extra foot space that you need to accomodate with your boot. I say buy at least 2 sizes up from your shoe size. If you have extra space, purchase a pair of neoprene socks, not only will this make your shoe fit better, it will also extend the life of your waders. Might need to go 3 sizes up. Also, it has been my experience, that if you place your wading boots on or near a heat source to dry them, they will shrink slightly.