I wear a size 11 in Nike or Adidas running shoe, but have always worn a 10 1/2 M in Timberlands. I got these in 10 1/2 M and they fit perfectly right out of the box. Took them for a long walk the first day and had no discomfort whatever. The sole flexes more like a running shoe than a boot. I would give them a 4.5 if I could. My only niggle is that the backs of my pants legs get hung up on the pull tab on the back of the shoe and that drives me nuts.