Normally 7 1/2 M and sometimes an 8 N. This 7 1/2 is a snug fit for my borderline slim feet so it may or may not be too tight for an average medium width. I've only worn it a few times so I'm sure it will do what leather usually does and eventually stretch to adapt to my foot. I've used it with shorts and jeggings,,,and even with a casual dress.  It seems very sturdy. I find it comfortable but I haven't used it yet for long periods of walking. I have danced in them and I had no problems with it.