Desired fit can depend on experience and performance.
So iLL recommends those who use women sizing to order 1 1/2 sizes up from your sneaker size. Example: If you wear a women's size 9 sneaker, select size W10.5 / M9. If you wear men's, So iLL recommends you order three sizes up. Example: If you wear a men's size 9 sneaker, select size W12 / M10.5.