What size pet door do I need?
Despite the best attempt to recommend the correct size of pet door by breed or weight, the only way to accurately select the proper size pet doors is by physically measuring your pet. There are two important measurements you need:
The rise of the door (how high off the ground the pet door is installed) should be set to 1" below the chest/belly. Some types of pet doors such as certain patio panels have limited options for the rise, so instead make sure the top of the door is set at the proper height based on the pet's shoulders.
The end goal is to have a 1" clearance at the shoulder width, a 1" clearance at the chest/belly, and 1" clearance at the back/shoulders.
As you may not find a door with the exact size you want, you should select size that will meet your needs and make allowances for your pet's age, weight, agility, and future growth. If you have multiple pets, you may need to purchase a larger door where the top is set to the height of larger pet's shoulders and the rise and bottom of the door can accommodate your shorter pets.