The proper way to determine what size bed your pet will need is to measure from your pets nose to the base of the tail. Once you have determined the length, you will need to add 9-12" to the length. To measure the height, you will need to measure your pet from the bottom of their paws to the top of their shoulders and add an additional 6-9". With these measuring guides, your pet will have the correct bed size for a great nights sleep!