How to Choose a Pet Door: Dog Doors and Cat Flaps

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A pet door lets your dog or cat come and go without you opening the door every time. This guide covers whether a pet door suits your home, how to size it, the main types (plain flaps, collar key doors, microchip doors, wall and sliding glass doors), security, training, and the microchip cat flaps that review sites have tried.

How we wrote this: the safety and training advice comes from the AKC, VCA Animal Hospitals, PDSA, the RSPCA and International Cat Care, all linked where they are used and checked on 31 October 2026. Product facts come from the makers’ own pages. Product notes come from review sites whose staff used the doors with their own pets: PetsRadar and Cats.com, plus Expert Reviews in the UK. We did not test these doors ourselves, and we do not show prices or ratings. We could not find a hands-on test of dog doors from a source we trust, so we do not pick a best dog door.

Is a pet door right for your home?

A pet door works best when the outside is safe. The AKC says a dog door should only open into a dog run or fenced area of your yard that is securely enclosed, and VCA says to only use an electronic door if your yard is free of hazards and securely enclosed with a fence. The AKC also says that even if your dog knows how to use a dog door, they should be safely inside the home when you are away.

Think about who else might use it. The AKC says that if you have toddlers who could copy your dog and exit through a dog door, you may want to wait until they are older, and that where wild animals visit your yard, a dog door could let unwelcome surprises in.

For cats, the question is whether they go outside at all. PDSA suggests considering keeping your cat indoors at night, because some studies show cats are more likely to be in road traffic accidents at night. If your cat stays indoors, an interior cat door can still be useful: Cats.com’s reviewer fitted one to an interior door to keep her dog out of the litter box room.

How to measure your pet

Measure before you buy, and size for your biggest pet. VCA says to measure your dog across the shoulders for the width, measure from the ground to the top of the shoulders and add 2 or 3 inches for the height, and use the largest dog as a benchmark if you have more than one. The AKC says a dog door that is too small could be frightening or even dangerous if your dog got stuck.

Makers measure in different ways: some use the chest or hips for width, some the back to the chest for height. Compare your measurements with the flap opening on the maker’s size chart, not the outer frame, and follow that maker’s own instructions. For cats, Cats.com suggests measuring your cat’s height at the shoulders and adding 1 to 2 inches for the minimum door height.

Types of pet door

• Plain flap doors. VCA says traditional pet doors open when the flap is pushed aside by your pet, the neighbor’s pet, a wild animal or a toddler. PetSafe’s Extreme Weather Aluminum Pet Door has a three-flap system and a slide-in closing panel, and fits most exterior doors 1 1/2 to 2 inches thick.
• Collar key doors. These open for a tag on your pet’s collar. VCA notes the problem: if your pet loses the collar, they cannot get back in, and if the collar falls into the wrong hands, that person can get into your house.
• Microchip doors. These read the microchip your pet already has, so VCA says they remove the collar issue. International Cat Care says a microchip cat flap will stop neighbouring cats coming into your home and upsetting your cat. The ones below run on batteries, and some connect to an app for curfews.
• Wall doors. Many doors can go in a wall with a tunnel or liner sold for that model. PetSafe’s own security article says wall doors are more secure than doors fitted in a door and harder to crawl through.
• Sliding glass door panels. VCA says renters can fit a temporary pet door, such as a spring-loaded insert for a sliding glass door, without damaging the property. PetSafe’s 81 inch patio panel, for example, sits in a standard sliding door track and can be taken out as one panel when you move.

Security

• Buy the smallest door your pet fits. PetSafe says the smaller the door, the harder it is for a person to squeeze through.
• Mind where it goes. The AKC suggests fitting a dog door away from doorknobs or window latches that someone could reach in and open.
• Check the lock. VCA says the door should lock securely at several points, so stray animals cannot push it open from outside even when it is locked.
• Know the limits of microchip flaps. PetsRadar notes that another cat may still get in by tailgating, following close behind your cat while the flap is open. A vet quoted there says to check a microchip flap regularly to make sure it is working.
• Check before you cut. VCA says many companies include a template you can tape to the door or wall before cutting, and Cats.com notes that once the hole is cut, it will not be easy to fill in if you change your mind.

Where to put a cat flap

International Cat Care says a cat flap can feel like a weak spot in a cat’s home defences, and suggests placing the litter tray as far as possible from outside doors and cat flaps. The RSPCA suggests potted plants around the cat flap, so it feels secure. International Cat Care also notes that some cat flaps can be set to let your cat out or keep them in at set times of day or night.

How to train your pet to use it

1. Open it up. The AKC says to hold the flap open or lock it in the open position, then go to the other side and use toys and treats to encourage your dog through. PetSafe suggests taping a cat door flap fully open at first, so your cat can see the way through.
2. Keep sessions short. PetSafe suggests two spaced-out 10 minute sessions a day for cats.
3. Never force it. The AKC says never to push your dog through the door or scold and punish them for not using it. Expert Reviews says it may take a cat days or weeks to get used to a new flap.
4. Program the chip first. For a microchip flap, Expert Reviews suggests programming your cat’s chip into the flap before you fit it.
5. Wait before leaving them alone with it. The AKC says to make sure your dog is very comfortable and confident going back and forth before leaving them unattended.

If your pet stays afraid of the door, or you are unsure whether going outside is safe for them, ask your vet.

Microchip cat flaps review sites tried

These are the doors we found that reviewers used with their own cats. We list maker facts and what the testers said, not our own verdict. Check that a door reads your cat’s microchip type before you cut a hole.

SureFlap Microchip Cat Door

SureFlap says it reads the chip on the outside only, so any animal can leave but only registered pets can come in. It stores up to 32 pets, runs on 4 AA batteries for up to 12 months, has a manual lock and an in-only setting, and can go in a door, window or wall with accessories. The opening is 5 5/8 by 4 3/4 inches. PetsRadar‘s tester Toby called it “reliable, robust and simple”; his cat popped the lock mechanism off, and he says SureFlap replaced it half a dozen times without any questions. Cats.com‘s reviewer said her cats had no issues using a SureFlap door and it paired quickly with her cat’s microchip.

SureFlap Microchip Pet Door

The larger SureFlap pet door is made for large cats and small dogs. SureFlap lists a 7.5 by 6 11/16 inch opening, a curfew mode, 4 C batteries for up to 12 months, a collar tag for pets without a chip, and fitting in doors, glass and walls. Expert Reviews’ UK tester said she had seen it fit a 7.5 kg cat.

SureFlap Microchip Cat Door Connect

The Connect version links to the Sure Petcare app through a hub that is sold separately and plugs into your router. SureFlap says it can set curfews, keep specific cats indoors, and runs up to 6 months on 4 AA batteries. PetsRadar’s tester said setup was very simple and the door fits tightly with little draft. One of his cats learned to pick the lock, and SureFlap sent a replacement panel that stopped it.

PetSafe Microchip Cat Door

PetSafe says it reads your cat’s 15 digit microchip, works with a separate key for cats without a chip, holds up to 40 pets, has locked, unlocked, in-only and out-only settings, and runs on batteries. It fits wood, PVC and uPVC doors, and PetSafe sells an adaptor for glass, metal or brick and a tunnel for walls. PetsRadar’s tester Megan found it easy to pair with her cat’s chip and said it opened every time once her cat got used to it.

Cat Mate Elite Microchip Cat Flap with Timer

Cat Mate says it reads a 15 digit microchip or a Cat Mate ID disc, programs up to 9 cats, has a 4-way lock and an LCD that shows the cat’s location and lock status, and runs about 12 months on 4 AA batteries. The flap is 5.7 by 5.7 inches, and the maker says it fits walls up to 4 inches thick without a liner. PetsRadar’s tester could not get it to pair with her cats’ microchips, but the ID disc worked, and she noted that the cat has to press its head on the flap to open it. If you buy one, check the chip pairing works before you fit it.

For the space on the other side of the door, see our best dog gate guide and how to choose a dog playpen. If you use a collar key door, our best dog collars guide covers collar fit.

Does your dog spend time in the yard? See how to choose an outdoor dog house, with welfare advice on sizing, bedding, shade and the signs of cold or heat stress.

To help your dog tell you when they need to go out, see our guide to the best dog potty bells, including how to teach your dog to ring them.

FAQ

Do microchip pet doors work with every microchip?

Not always. PetsRadar’s tester could not pair two Cat Mate flaps with her cats’ chips and used the collar disc instead. Check the maker’s list of supported chips, and program the door before you fit it.

Can a burglar get through a dog door?

A large door can be a risk. PetSafe says to buy the smallest door your pet fits through, and the AKC says to place the door away from latches and doorknobs someone could reach. A door that locks at several points helps.

Can I fit a pet door in a rented home?

Often, without cutting. VCA says renters can use a temporary insert that fits in a sliding glass door frame. Ask your landlord before you cut any door, wall or glass.

Should my cat be able to go out at night?

PDSA suggests keeping cats indoors at night, and many microchip flaps have a curfew setting. Talk to your vet about what suits your cat.