Buying Guide

How to Choose a Cat Door

Know the Weight and Size of the Cat
A side by side image of a cat going out of a cat door on left and right sides of the image.

One basic guideline for choosing a cat door is to know the weight and size of the cat(s) using the door. Most cats can maneuver through small spaces, so you won't need to cut a giant-sized hole into a door just for their convenience. 

Cat doors come in varying sizes, from about 5 to 10-inches wide and high. A smaller cat, under 12-pounds or so, can go through the smaller cat doors. Larger cats, over 12-pounds, will need a bigger cat door.


If your cat allows it, measure your cat’s height and width to match it to the inside dimensions to a cat door. Read the dimensions associated with any cat door model carefully before you choose one, and visualize your cat going in and out of that door.


Other pets of varying sizes can also use a cat door to come inside your house or structure. Choose a size as small as you feel would be most comfortable for your cat. 

Choose a Standard Cat Door
Cat moving through a basic flap cat door.

A flap opening is a simple concept for any free-roaming cat. If you have no need to control a cat's outdoor or indoor access, choose a flap model for doors or windows. 

Most flap doors have magnetic weights in the flap to secure it to the frame. This prevents rain, dirt and debris from blowing indoors while allowing the cat to nudge the flap open in any direction. 

Note: Anything your cat brings home from a hunt can also enter through the flap door, as could a neighbor's pet, a small dog or random critter that may follow your cat home.

Choose a 4-Way Cat Door For Control
Cat entering a home through the 4-way model of cat door.

If you need to keep your cat indoors or outside for any reason, a 4-way model of cat door is a good choice. The four ways you can set access on this kind of cat door are: 

  • Cat goes inside only
  • Cat goes outside only
  • Cat can go in or out 
  • Cat door stays closed 

Choose a Microchip Reader Cat E-Door
The microchip reader variety of cat door.

Some models of cat doors, or "e-doors," come with a microchip reader. E-doors give your cat exclusive access. With a chip reader built into the frame, the e-door can only be opened by a cat wearing a collar with the matching chip.

This is a good choice if there are other animals in the vicinity of your home that may be curious about using the door.  

Note: A microchip reader door can't prevent your cat from dragging things indoors with its mouth or paws, but it does provide more lockout control for other small animals.

Choose an Interior Cat Door
A cat going through an interior cat door.

A cat door placed on an interior door in your house, such as a laundry room or basement area, will let you keep a litter box and the associated smell away from your living quarters. The cat will have access to the litter box as needed, in only that room. 

Choose a Prehung Door With Cat Door
A prehung door with a cat door at the bottom.

If you don't want to install a cat door into an existing door, choose a prehung, all-in-one door. Simply remove an existing door from the hinges and install the prehung version. 

Prehung doors come with a variety of cat door options built in. You can select or order the standard flap model, a 4-way version or the microchip-reader cat door opening on a prehung door. The 4-way version is usually included on most in-stock prehung doors.

Choose an Insert Cat Door for Windows
An insert cat door for a window.

Another cat door option is the "insert" variety. This type of pet door insert fits into a window's sash where the glass pane would normally go, allowing your cat access to the outside through an approporate window rather than a door.

This is a good choice if in/out access would be better through a window or if you don't want to cut into your space for a custom-made door. For instructions on installing a pet door into an existing door, see our guide on How to Install a Dog Door.

With its hunter instinct and personality, a cat will be happy enjoying expanded freedom of movement when you install a cat door. As a caring and responsible pet owner, you will be happy knowing you've chosen the right kind of cat door for your home.