Measure Your Pet!
Measure Your Pet's Width:
1. Open your door or sliding glass door as wide as your pet needs to comfortably walk through. Using the door opening size rather than measuring your dog's width with a ruler ensures that you allow a little wiggle room for the final dog door or cat door flap size.
2. Try using a treat to motivate your pet to walk through the door or sliding door opening you make.
3. Measure the width of the opening you have made.
You need the flap door to be at least that wide. It doesn't need to be wider, but it should not be any narrower. Pay special attention if your dog has a particularly deep chest or is low slung and adjust your doggie door size selection accordingly.
For pet owners with more than one pet, make sure you do this with your widest and tallest pet so that the doggy door size you choose works for all your pets.
Measure Your Pet's Height:
1. Have your pet stand completely upright. For multi-pet homes make sure to do this with your larger dog or cat.
2. Grab a tape measure or ruler and measure the height from the floor to the top of your pet's withers (the highest point of their shoulders).
3. Now that you have your dog's height, let's factor in step-over...
1. Consider how high off the ground you want to install your pet door. The distance from the ground to the bottom of the pet door flap is called the "Step-Over."
2. Add the Step-Over height to the height of your pet measured earlier. The top of the flap should be mounted at least 1" higher than this.
3. In no case should the "step-over" exceed 1/3 of the height at the withers - the lower the "step-over," the better. Adjust accordingly until you decide on a step-over height and dog door size that will allow at least 1" above your pet's withers.
Note that Step-Over can get a little tricky to customize for installations in locations such as French doors or sliding doors which may have less wiggle room for Step-Over height without risking the integrity of the door frame/glass.
A great customizable option for sliding glass patio doors is the Endura Thermo Panel 3e which features user adjustable Step-Over height ideal for long-legged dogs (like Great Danes and German Shepherds) or short-legged dogs (like corgis). This patio panel insert has all the energy efficiency of the Endura Flap with the convenience of an adjustable Step-Over for maximum ease of use.
Pay special attention if your dog has a particularly deep chest or is low slung and adjust accordingly.
If you have a larger/taller dog sharing a pet door with a smaller dog or would just like to have a taller pet door:
On the far right of the image above is a pet door with a "high aspect ratio".
The best dog door that allows for a high aspect ratio is our very own high quality, energy efficient Endura Flap. It allows for a nice tall flap height for tall dogs to move through comfortably and a small Step-Over that small dogs can clear. Check out the size chart and browse the different sizes to choose the perfect size pet door for your pets. The high aspect ratio Endura Flaps come in sizes Small-Extra Large, so there are lots of options for choosing the Step-Over that works for you and your pets..
Why is measuring correctly so important?
We are trying to make sure that the pet door is as accessible as possible for your pet, large dogs and small dogs alike. This also means ensuring that the door remains accessible throughout the entirety of your pet's life. Pet door sizes that were accessible to your your pet's during their youth may become more difficult for them as they age.
There may come a time when your pet won't be able to use their pet door. Maybe they've developed hip problems or an injury. Maybe they're just old and can't move very well. This is where a nice low Step-Over comes in handy so they don't have to strain themselves crawling into a door that is too high off the ground for them in their old age.
So what is properly sized pet door? Well, the top of the opening is at or above his withers so he doesn't have to crouch. The width is as wide as he is or a little wider. And the 'step-over' is as low as possible while still keeping the top of the opening up at or above his withers. A properly sized door means all you'll need to do for maintenance is purchase replacement flaps if necessary, no need to replace the entire door assembly as your pet ages.
This is what 'high-aspect ratio' pet doors are all about. For a given width, you get more height which means you can get the step-over lower to the ground for easier access later in life (also a great bonus for giant breeds and smaller breeds sharing).
Of course, it all depends on your unique situation. Maybe your pet is a youngster and you're going to move to a new place soon. In that case, mount the pet door at the correct height (at or above his withers). He'll be able to use a higher 'step-over' until you move, and you can easily get a properly sized pet door at your next house.