Your carefully choice will avoid plenty of inconvenience of returns. Please choosing the size by the measurement of your pet (The Chest and Back), not the weight or breeds simply. You can find a Size Chart on every product page. If your pet is still growing, please take this into consideration when choosing the size. Size Attention: 1.If any of the measurements are "between" two sizes, choose the larger size is recommended. If your measurements are toward the upper end of the range given for a particular size, you may also want to choose the larger size, as you may also wish to do for heavily coated dogs to accommodate all that fur. 2.Take each measurement a bit loosely, so there will be room for your dog to move and breathe, but not too loose. The clothes is designed in standard sizing, every pet has their own body shape, it is difficult to make sure every clothes can fit all the pets perfectly, so we strongly advise that you need to choose size based on our size information seriously, not on your experience and what you normal think abou size since every product has different size defination.