It is simple to determine the minimum width needed by your pet to pass through with comfort. Open a sliding door just wide enough to have them walk through with a minimum of one-inch clearance gap on each side. This width including gaps is the minimum size flap width you require.
Step 2 –Determine Flap Height
The top of the flap should be placed at least as high as the top of the tallest pet’s shoulder, take a measurement from the floor to that point.
Step 3 – Determine Door Size
“In-The-Glass” Doors come in four sizes. Using your previous measurements, select a door at LEAST as wide and tall as you need, larger is better than too small.
Step 4 – Determine Direction
When OUTSIDE, determine which side your sliding door opens, is it from the Left or Right?