THERE IS NO STANDARD SIZING SYSTEM FOR PET CLOTHING. Pet clothing is based on MEASUREMENTS and not weight or breed! Before placing an order, please measure your pets’ waist and Compare them to the sizing chart provided in the photos and size options. Each and every different brand/style of pet clothing has its own sizing system. One brand size ‘Medium’ can very well be another brand size ‘X-Large’. Each brand, item and style has its own unique sizing chart and no two charts are the same.