Cat Doors: Choose the Perfect One

What makes a cat door different than a dog door? Technically, not a whole lot! Cat doors are usually rigid flaps, and smaller than dogs doors, but logistically they work the same way. Cats can use dog doors, and tiny dogs can use cat doors, it's all about the sizing! Check out this helpful measurement guide to get the right fit.

this cat door 4-way locking chart shows how electronic cat doors and microchip cat doors can have multiple settings

What is a 2-way lock vs a 4-way lock?

Cat doors usually have a 2-way lock or 4-way lock feature instead of a slide in locking cover. A 2-way lock is the normal "locked" or "unlocked" system. The 4-way lock feature adds "in-only" and "out-only" for added convenience depending on your schedule!

An example of when to use these types of locks is if you want your cat to come in at night and stay inside until you let them out in the morning. You would switch it to "in-only," that way once your cat comes inside (perhaps for dinner) they can't turn around and go right back outside.

The 4-way locking mechanism can also be incorporated in an electronic cat door. In this case, the 4-way lock will override the electronics. If the cat door is set to 'out only' your cat will not be able to enter. The Cat Mate "Elite" Electronic Cat Door, for example, features a 4-way locking device should you choose to completely lock or unlock the door. In general there are no real 4-way locking dog doors as this is something you only find in cat flaps.

How do you know which size cat door to get for your cat?

We recommend that you test it out! The size of one of the Cat Mate Cat Doors, for example, is 5 3/4" w x 6 1/4" h. If you take a piece of paper or cardboard, you can cut a hole that size and encourage your cat to step through that hole with some food or a toy.

Don't think your cat will fit through that opening? You might be surprised. Cats are quite talented at getting through tight spaces, and usually seem to enjoy it! You don't want your cat to have to squeeze, but usually they can comfortably get through much smaller openings that we imagine. Here is a smaller sized cat casually squeezing through a small crack:

You want to make sure that when you install your cat door, you place it low enough to the ground that your cat can comfortably get through even when they get older and less agile. You don't want them to have to jump through!

There is nothing wrong with getting a small size dog door for your cat if you want them to have a bit more room. Something you'll want to consider when getting larger pet doors for your cat is that the flap might be heavier and therefore more challenging for your cat to push open. Some cats get along just fine with even large dog doors, but others are more timid and will refuse to use them!

Where can you install your cat door?

You can install these anywhere; you can have a cat door for windows, a cat door for doors, a cat door for walls, or all three! Cat doors tend to be smaller than dogs doors so they can fit more comfortably in windows or even through cabinets to hide the litter box. Cats are also much more agile than dogs, so usually all sash window cat doors will work well! Usually if you need to make height adjustments, you will add a step on one or both sides of the door and the cat can jump the rest of the way.

Though maybe not for the most timid of cats, the Endura Flap in the Thermo Sash 3e cat door for windows is a great option as the Endura Flap is flexible, which can be more favorable for pets. As a highly insulated cat door, the Endura Flap saves energy (and money!), keeping your home protected from the elements. It's one of the best cat doors out there!

You might also consider a microchip cat door in a thermo panel to keep unwanted critters out of your home. The Thermo Sash SureFlap Microchip Pet Door is perfect for homes where intruder animals are a concern! The SureFlap Microchip Pet Door uses a collar key or your cat's embedded microchip to grant access to your cat only. No more neighbor cats or other critters (ike those pesky raccoons!). A chip activated cat door is a great way to give your cat the freedom to come and go without compromising the security of your home.

If you are still unsure which kitty door is the best fit for you and your cat, you can also take a look at this helpful article on choosing the right door for your pet!
Rachel Long

Written by

Rachel Long

The Team is dedicated to providing the highest quality pet doors. As dog and cat lovers ourselves, we aim to write about the topics that matter the most to you and your furry friend. If you have any questions, please contact our customer service team. 🐢🐱


  • Hi Michelle,

    You can see our full selection of cat doors here:

  • Hi! Do you guys sell these?


Leave a comment

Please note, comments must be approved before they are published