Step 1:
Measure your pet from the top of the shoulders to the chest, just behind the front legs.

Step 2:
Determine your pet's weight.

Step 3:
Select the correct door size based on your pet's measurements and weight.

Step 4:
Do not pick a dog door using only your dogs weight. Measure your dog to make sure they will fit. It is a good ideal to make a cardboard cut out of the dog door flap size to see if your dog will fit. If you have any question, go larger!