How to Choose the Right Size Pet Door

    Your Pets' Needs:
    Each pet is an individual as far as size, age, and agility. If he has long legs, he can step higher over the threshhold. If he is old or obese, he may be less able to hop over the bottom of the door. All of these factors affect which size door is appropriate for your pet.


  • Pet Door Height::
    There are two measurements to consider when deciding on the height of a door: The height of your dog or cat at his shoulders (so he doesn't have to scrape his back as he pushes through the door) and the height of the step-over that he must make.

      height of your dog
    • To measure your dog's height, stand him next to a wall and mark a small mark with your pencil at the height of his tallest point on the back. (In most breeds this is the shoulder area although some wolfhounds and greyhounds have a "roach" that is higher). For cats, there are usually only one or two sizes offered: a "cat" door (or small size) or (sometimes) a large cat size. No need to measure. Unless your cat is really large, the "cat" door will be appropriate.

      height of the step-over or "RISE"
    • To decide on the rise of your door, we need to consider how long your dog's legs are or how agile he is. A young, tall doberman can probably step over a rise threshhold of 6-9" with ease. A short, old basset hound might have difficulty with a 3" rise. If there is a step on either side of the door, the "step-up-step-down" is also more difficult and the "rise" of the door should be made smaller to compensate.

      To test your pet's step-over height, place a 2x4 or 2x6 in the doorway and call your pet over it to test his ability to get over it with ease (without jumping).

  • Pet Door Width::
    Some dogs are fat, others slender. To measure the width of your dog, swing an interior door not-quite-shut, then ask your dog to come through it slowly. Hold the door so that it opens gently and you can measure the width of the opening as he comes through. Add 1" to that width.


  • Determine the Flap Size You Need
  • The door size will be the height of your dog (plus 1") minus the rise height. That is a 24" doberman who can step over a 9" rise will require a door whose flap (or interior meaurement) is:
    25" - 9" = 14" high. The width should be at least his width (per your mesurement) plus 1".


  • More than one pet?:
    Measure BOTH pets as above. Use the height of the largest dog (plus 1") for the height of the pet door. Use the Rise dimensions of the shortest dog. Use the width of the widest dog.

    A 24" doberman with a 14" basset who can only step over a 3" rise would look like this:
    25" - 3" = 22" flap height.
    The basset is fatter, so get a flap that is wide enough for him to use with ease.

    Very small and very large pets: If there is a VERY LARGE disparity between the sizes of the pets such as a cat and a doberman, you may need to mount two different doors. (The weight of the flap may be too much for the tiny dog or cat to push.) You may know this ahead of time and purchase two doors right off the bat, or you may want to try the large dog door and see if the terrier or cat will have the strength and tenacity to push it. Remember, however, that you want your pet to enjoy exiting through the door. Don't make it a chore, or the consequences could be housebreaking issues.

  • Choose a Door
    Now look at the available sizes of doors. (You have probably already guessed that there may not be one exactly as you measured.) Choose the door that most closely fits your needs or larger. Do not choose one that is smaller than any measurement recommendation.

  • How to Measure for Mounting
    The top of the flap must be placed at least as high as the top of your pet's height measurement (plus 1") Our 24" doberman's door would be mounted with its flap 25" off the floor.

    The mounting height of the patio pet doors is pre-determined. You'll have to choose the one closest to your needs without the flexibility to change that measurement.



Cat Doors: Sizing