The stretch in this sock is very generous, the width fit my foot nicely (my foot measures 9” around the widest point) but the length was not great. The final product was intended to be a little “thicker” than I normally make, because the recipient (my mommy!!) is not a “sock person” unless she’s wearing them to bed. I went with the large shells because I didn’t have to worry about them being uncomfortable in her shoes.