STEP 1
Determine Flap Width

A simple way to determine the minimum width needed by your pet to pass through with comfort is to open a door and have them walk through till they have a minimum of one inch clearance. Measure the gap and this will be the minimum size of flap width you will require.

STEP 2
Determine Door Rise

To find the rise you need, simply measurement from the floor to the lowest part of your dog's chest or stomach. With this measurement you can tell you where to place the "bottom" of your dog door.

STEP 3
Determine Flap Height

It is recommended the top of the flap be placed at least as high as the top of the tallest dog's shoulder, so measure from the floor to that point

Now that you have the Rise & Height measurement, you can determine the flap height with a little easy math.

Door Height - Door Rise  = Flap Height

Here is an example!

Your Pet is 23 inch's tall

Their lowest point is 7 inch's from the floor

So your flap height size would be: 23 -  7 = 16