There are no standard sizes for dog clothing. We highly recommend you measure your pet precisely to ensure an accurate fit. It is not reliable to purchase items based on your pet's breed or weight. Please purchase our products according to your dog's measurements, not the clothing size. Remember, if the dog is in between sizes, it is often better to choose the larger size (one step up). The most important measurement is the chest size. If the chest size is ok, the rest of the measurements will not make a huge difference. Our sizes are much smaller compared to other retailers.