Figuring out exactly how do you measure for a dog door is the first thing you need to tackle before you even look at different models or styles. It's one of those "measure twice, cut once" situations where a tiny mistake can lead to a lot of frustration—either for you during the installation or for your dog when they're trying to squeeze through a hole that's just a bit too tight.
If you get the measurements wrong, you might end up with a door that's too high for a senior dog to step over or too narrow for a growing puppy who eventually fills out. Let's break down the process into simple steps so you can get it right the first time and keep your pet happy.
Get Your Tools and Your Dog Ready
Before you start poking around with a tape measure, make sure you have everything you need. You'll want a standard metal measuring tape, a pencil and paper to jot down the numbers, and—this is the most important part—some high-value treats.
Most dogs aren't exactly thrilled about having a metal tape pulled out near their face or body. It can be a little intimidating for them. Having a partner to hold the dog steady or offer treats while you work will make the whole thing go a lot smoother. Try to find a flat, level surface where your dog can stand naturally. If they're hunched over or sitting, your numbers are going to be way off.
Measuring the Width of Your Dog
The first number you need is the width. You're looking for the widest part of your dog, which is usually the shoulders or the hips. For most breeds, it's the shoulders.
Stand over your dog and look down to see where they're the broadest. Take your tape measure and gently measure across that point. Don't pull the tape tight against their fur; you want a measurement that represents their actual physical frame.
Once you have that number, add at least two inches to it. This extra space ensures they aren't rubbing against the sides of the flap every time they go out. If you have a dog with a particularly thick coat or a breed that tends to gain weight easily, you might even want to add three inches just to be safe. Freedom of movement is the goal here.
Finding the Correct Height
Next up is the height. This is where a lot of people get tripped up. You aren't measuring from the floor to the top of the dog's head. Instead, you need the measurement from the floor to the top of the shoulders (the withers).
The reason for this is pretty simple: dogs duck their heads when they go through a pet door. As long as the top of the flap is at least an inch or two above their shoulders, they'll be able to navigate it comfortably.
To get this measurement, have your dog stand tall. Place the end of the tape measure on the floor and bring it up to the highest point of their shoulder blades. Again, write this number down and add about two inches to it. This "shoulder height plus two" rule is the industry standard for a reason—it works for almost every dog.
The "Rise" Is Just as Important
The "rise" is the distance from the floor to the bottom of the dog door opening. It's the "step-over" height. If you install the door too high, your dog will have to jump or struggle to get through. If it's too low, you might be compromising the structural integrity of your door or letting in more drafts than necessary.
To find the ideal rise for your pet, measure the distance from the floor to the lowest part of their chest or belly. You generally want the bottom of the dog door to be one to two inches lower than this point.
For younger, athletic dogs, a higher rise is usually fine. But if you have a senior dog with arthritis or a breed with short legs (like a Corgi or a Basset Hound), you want that rise to be as low as possible. You have to think about the long term here; a five-inch step might be easy for your dog today, but will it be easy for them in five years?
Accounting for Growth and Multiple Pets
If you're wondering how do you measure for a dog door when you have a puppy, you have to do a little bit of guesswork based on their breed standards. Look up the average shoulder height and weight for an adult of their breed and gender. It's always better to buy a door that's slightly too large for a puppy than one they'll grow out of in six months.
If you have multiple dogs of different sizes, you have a bit of a "Goldilocks" problem. You need a door that is tall enough for the largest dog but has a rise low enough for the smallest dog.
In this case, measure your tallest dog for the top of the door and your shortest dog for the rise. This usually means buying a larger door and mounting it lower on the house door or wall. Just make sure the flap isn't so heavy that the smaller dog can't push it open!
The Cardboard Template Trick
If you're still feeling nervous about the numbers, there is a foolproof way to test your measurements before you buy anything. Take a piece of cardboard and cut out a hole using the width and height you've calculated.
Hold this cardboard up and encourage your dog to walk through it using some treats. Watch their movement closely. Are they hitting their back? Do they have to squeeze their shoulders? If they move through it naturally without hesitating or scraping the sides, you've nailed the measurements. If they seem hesitant or struggle, you might need to go up a size. It's much cheaper to cut a second piece of cardboard than it is to return a heavy-duty dog door.
Measuring the Installation Surface
Once you know the size of the flap you need, you have to measure the spot where it's going. Whether you're installing it in a solid wood door, a metal door, or through a wall, the thickness of that surface matters.
- For Doors: Measure the thickness of the door itself. Most standard exterior doors are about 1 3/4 inches thick. Most dog doors are designed to fit this, but some "thin" doors or screen doors might require an adapter.
- For Walls: If you're going through a wall, you need to know the depth from the interior drywall to the exterior siding. This often requires a "wall kit" which acts as a tunnel to bridge the gap.
Make sure there is enough flat surface area on the door or wall to accommodate the entire frame of the pet door, not just the flap. Some frames are quite wide, and you don't want to realize too late that the frame is hitting the decorative paneling of your door.
Common Mistakes to Avoid
There are a few pitfalls that people fall into when they're figuring out how do you measure for a dog door. First, don't assume weight is the only factor. Many manufacturers categorize doors by weight (e.g., "Medium: up to 40 lbs"), but dogs are shaped differently. A 40-pound Bulldog is much wider than a 40-pound Whippet. Always go by the physical dimensions of the dog rather than just the weight limit on the box.
Second, don't forget about the "step-out." If the door leads to a porch that is lower than your interior floor, the "rise" effectively becomes much higher on the way back in. You might need to build a small step or ramp on the outside so your dog doesn't have to pull off a massive vertical jump just to get inside.
Lastly, don't ignore your dog's personality. A shy or nervous dog will likely want a larger opening so they don't feel "trapped" or squeezed as they pass through. A little extra breathing room goes a long way in making the training process easier.
Final Check Before You Buy
Take those final numbers—the flap width, the flap height, and the rise—and compare them to the "opening dimensions" listed on the product you're looking at. Remember that the "outer frame dimensions" are different from the "flap dimensions." You care about the flap size for the dog's comfort and the frame size for the installation.
If you're right on the edge between two sizes, always go bigger. It's much better for the door to be a little too large than even a fraction of an inch too small. Once you've got those numbers locked in, you can move forward with confidence, knowing your dog is going to have a perfect, custom-fit entrance to the great outdoors.