A method for determining best fitting footwear includes acquiring a static 3D scan of a user's feet; generating a static 3D model of the user's feet; modifying the static 3D model to generate a dynamic 3D model that corresponds to changed shape of the user's feet when performing an athletic activity; identifying a footwear that best matches the dynamic model; and informing the user of the footwear that best matches the dynamic model. Optionally, the static 3D scan is retrieved from a database, or generated on the fly, or based on images from a mobile device. Optionally, the dynamic model takes into account a type of athletic activity, a weight distribution of the user, a load on the feet of the user, and a motion mechanism and strike type. Optionally, the dynamic model modifies a foot length, a foot width at ball, and a foot width at bottom.