Because of the large number of brands we carry and the various sizing they use, we have made an attempt to offer some consistency to aid in searching our site for the right fit. Although our adult sizes can run from XS to XXL, you will find that M(edium) is a general women's sized and labeled sock and L(arge) is a general men's sized and labeled sock. Because our feet are all uniquely awesome and different (who is that Morton person and how did they get a toe namesake?) please check the Fits approximate shoe size: area on each product page to ensure the sock is right for you. If you are still unsure and would like some guidance please contact us and Mooselow, our resident Sockologist or a member of our Customer Care team would be happy to help when we are not on break or wandering about within Algonquin Provincial Park. More fit and sizing info is available here.