They are not a performance fit, the sizing is more of a xs, sm, med, lg format. I think the "smalls" fit a woman's 6/7. The pair I borrowed for a day seemed true to fit. I wear a pretty true, though low-volume, 6.5, and wore the smalls for hours and hours. They felt a little big, but I have skinny feet, and they are supposed to fit up to a 7. I'd say try them on, with socks, without, as the material is pretty soft and offers a unique, but comfortable, experience.