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What Size Dog Door Do I Need? Facts, Tips & FAQ

Kristin Hitchcock

By Kristin Hitchcock

a dog walking through a pet door

Dog doors can be a helpful addition to your home, no matter what size pooch you may have. You can purchase a dog door online or even make one yourself if you have some experience with DIY.

When installing a dog door, many owners are confused about the right size for their pooch. If this is you, you’ve come to the right place! A good rule of thumb is to ensure the distance from the ground to the start of the flap is no more than 1/3 of your dog’s height. Keep reading as we explain further.


What Size Dog Door Do I Need?

Choosing a dog door size is surprisingly simple. First, measure your dog’s height at the shoulder. Next, add 1 ½ inches. This will provide plenty of clearance for your canine, allowing them to fit comfortably and giving them a bit more room to grow.

If you have the height of the dog door, that’s usually the only information you need. However, you should consider the width, too, especially if your dog is very skinny or stoat. Dog breeds like bulldogs or mastiffs may need a particularly wide door, for instance. Be sure your dog has at least one inch of clearance around their body. Otherwise, they may get stuck! You can ensure this by measuring your dog’s width at their thickest point and then adding one inch to it.

Larger dogs won’t need to worry about the step-over distance, as they can almost always clear it. However, for very small dogs, this becomes an issue. Ensure the distance from the ground to the start of the flap is no more than 1/3 of your dog’s height. Otherwise, they may have trouble getting over it. Senior dogs may also need a smaller step-over distance if they have mobility problems.

Select a dog door that meets or exceeds all of these measurements. Larger doors are often better, though you don’t want to go over by too much. Otherwise, the flap may be too heavy for your dog to open. Generally, sizing up by one size is fine. But you don’t want to size up by more than that.

basset hound dog waiting by a door
Image Credit: Danita Delimont, Shutterstock

What is a Medium Dog Door?

The exact specifications for a dog door will depend on the company. You should always check the exact specifications because they will vary. You want to be sure that your dog will fit through the dog door with ease, and measuring is the only way you can do that.

However, generally, most medium-sized dog doors will have a passage opening of 8 ½ inches by 16 inches to 10 ½ inches by 18 inches. Usually, these doors are designed to work for medium-sized dogs, such as Beagles, Poodles, Cocker Spaniels, and similar dogs.

Do not simply choose a medium-sized dog door if you have a medium-sized dog, though. Measuring is still necessary.

What is a Large Dog Door?

A large dog door is generally designed for fairly large dogs. For instance, Labradors, German Shepherds, and Golden Retrievers all fit into this category. The dimensions of these doors are usually around 11 inches by 27 ½ inches to 13 inches by 29 ½ inches. Of course, what exactly counts as “large” will vary.

Just like with the medium dog door, be sure you measure your dog. Large dogs vary widely in size, with many people considering any dog over 70 pounds to be large. However, a 70-pound dog and a 140-pound dog will need vastly different dog doors.

Measuring is the best way to ensure you’re purchasing the correct dog door for your canine.

a dog peeking out on the pet door
Image Credit: VictoriaG1988, Shutterstock

What is a Small Dog Door?

There is no overall standard for sizing dog doors. Therefore, companies use whatever standard they come up with.

That said, small dog doors usually range from 6 ½ inches by 12 ½ inches to 8 ½ inches by 14 ½ inches. Most companies have their small dog door measuring in this range. Be sure always to double-check, though.

Small dogs like Chihuahuas, Pomeranians, and Yorkies often need these dog doors. Be sure to pay extra-close attention to the step-over distance, too. If the door is too far off the ground, these canines may be unable to step over it.

How Far from the Bottom of the Door Should a Dog Door Be?

The distance between the bottom of the door to the start of the dog door is called the “step-over” distance. In other words, it’s the distance the dog needs to step over to go through the dog door. The distance can vary depending on the size of your dog. Different dogs can step over differing heights. Therefore, you’ll probably need to personalize the distance for your canine.

The distance should not be more than 1/3 of your dog’s height. This is the absolute maximum that many dogs can step over. If your dog has short legs (like a Beagle or Corgi), that distance should be even shorter. In these situations, consider installing it closer to 1/5 of your dog’s total height.

In many cases, we recommend installing it slightly lower than the maximum, though. If your dog has normal-sized legs, consider installing it at no more than ¼ of your dog’s overall height. Also, consider that older dogs may have mobility issues and may be unable to step over very tall obstacles. In this situation, you should install the door even lower.

Never install a dog door less than 3 inches from the floor. Water may seep in if it is any lower, ruining your floors. Furthermore, anything lower than this may be small enough for a rodent to clear, and you don’t want rats getting access to your house through the door.

inside view of a black pet flap on a light wood door
Image By: Inked Pixels, Shutterstock

What is the Easiest Doggie Door to Install?

Installing a doggie door is often difficult for most people. However, modern doggie doors are made to be easier to install. Just like with most products, doggie doors have improved a lot over the years.

Sliding dog doors are one of the easiest doggie doors to install. For these doors, there is no need to cut into the wall or door, as they are installed on a sliding door track. However, you do need to have a sliding door. Some renters may also be able to use this option, as it doesn’t permanently change the door it’s installed in.

Almost all standard dog doors require some DIY knowledge, or you can hire a professional to install them. If you want a quality door installation and don’t have much DIY knowledge, our recommendation is to hire someone with experience. These doors typically require a permanent installation, which you’ll need to consider if you plan on moving anytime soon.

How Do I Know What Size Doggie Door to Get?

The only way to know what size doggie door to get without any question is to measure your dog. You should measure your dog’s height at the shoulder and their width at their thickest point. Then, ensure you choose the next size up from your dog’s measurements. They should get at least 1 ½” clearance for their height and at least 1” clearance for their width (total, not on both sides).

You can also do the “cardboard” test. Simply put, get a big piece of cardboard and cut a hole that matches the same dimensions of the door you’re thinking about buying. Then, attach a leash to your dog’s collar and encourage them to step through the cardboard cutout. If your dog seems a bit unsure, feel free to use high-value treats.



Sizing a pet door is not challenging. However, it does require taking careful measurements to ensure that you pick a dog door that is the correct size. Having a door that is too small may result in significant safety issues. You don’t want your dog getting stuck!

Be sure to consider the step distance, too. Dogs with short legs won’t be able to step over much of the door as dogs with longer legs.

Featured Image Credit: Cole Giles, Shutterstock

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