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Pet Door Sizing

Too big is better than too small – if a dog has to squeeze through an opening, it can put dangerous stress on his or her back and knees
Size for your tallest dog – buy and mount the door for your tallest dog, and make accommodations to assist smaller pets (such as the Pet Step accessory).
For tall dogs, the door should be off the floor – most dogs lift their feet up when they walk, naturally going through a door several inches off of the floor with ease.
If you’re not sure, do some testing – we suggest performing a simple simulation at home so you can quickly and easily see how well your dog will react to any of our doors

Pet Door Dimensions

Pet Opening – The smallest opening through which your dog will have to pass when using the door. This dimension is used for properly sizing the door for your dog.
Rough Opening – The size of the hole in your door or wall needed to accommodate the RANGER dog door.
Frame Size – The overall size of the frame on the pet door. This will vary between mounting styles.

This sizing method requires a big piece of corrugated cardboard. Start with the pet opening size you think is most appropriate for the pet in mind.
Cutout either the 6”x10” (small), 9”x13” (medium), 11”x17” (large), or 16” x 23” (XL) pet opening rectangle out of the cardboard up high and fold it at the bottom so that when the piece of cardboard is placed in a doorway, the top of the hole of the rectangle is approximately one inch to an inch and a half higher than your pet, at the withers or shoulders.
Step on the folded end of the cardboard, and invite your pet through the opening. Watch for clearance high and low.
If the size of the cutout you try is inappropriate, change to the next size up or down as required. Remember, it is always better to err on the side of being too large.