What size flap do I need for my dog or cat?

You will need to weigh and measure your pet. If you have more than one pet, measure and weigh your biggest pet.

If you have a puppy, you will need to estimate how big he will be when he's full grown.

Step 1: Weight

Refer to The Ideal Pet Door Size Selection Chart below. The weight is only the starting point. A fat short dog and a tall slim dog may weigh the same but will need a different size door and rise.

Step 2: Height and Width

To determine the correct size door measure the width (A) and height (B) of your pet:

1. Width: Measure the widest point of your pet's shoulder. You will need a flap about 1/2 inch wider, so he can comfortably get through the door
2. Height: Measure from the top of your pet's back (just behind his head) to the bottom of chest.

If you're not sure what size you need, take a large piece of cardboard and cut out a "test flap" from it — making it the height from the ground that you think your pet can comfortably go over. Make him go through the opening.

How to measure for a patio door

Measure your frame from inside the grooves where your door slides.

How to measure for a window sash door

Measure your double hung window inside the grooves where your window slides up and down.