Using a ruler, measure the length of your pets paw from the bottom base pad (paw) to the end of the nails, then measure the width of your pets paw, this is much easier to do when your pet is standing, stand you pet on a piece of paper then do the markings on the paper, the top including nails, heel and sides of the paw, then get your ruler and check the size chart. The socks do stretch a little, they are hand washable cold water, lay flat to dry. I only sell high quality pet items, these socks are adorable and are a excellent quality, do`t be fooled by the cheap imitations.