Size does vary with the color and the material the shoes are made out of. I wear a size 8. Bought the GoWalk canvas, stretchy pair first in an 8 and they fit perfectly. Thought I would try a 2nd pair in the "Autumn", and size 8 is tight on one foot only. Everyone has one foot that is slightly larger than the other, but these are tight on my smaller foot, which I find weird. I am hoping the shoes will mold to my feet and have some give as I wear them. Will see if they provide warmth in colder weather. Grey/silver are my favorite colors and I am so excited both are in right now and I can find loads of grey/silver shoes.