SureFlap Pet Door vs Cat Flap: Which Size to Get? (October 2026)
Choose the SureFlap Microchip Pet Door for a larger opening or small dog; choose the Cat Flap for a cat-sized opening. Both read compatible implanted microchips on entry and store up to 32 identities.
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Choose the SureFlap Microchip Pet Door for a larger opening or small dog; choose the Cat Flap for a cat-sized opening. In this SureFlap pet door vs cat flap comparison, the main difference is the flap opening, followed by battery size and locking options.
The Pet Door opening measures 6 11/16 inches high by 7 inches wide. The Cat Flap opening measures 4 3/4 inches high by 5 5/8 inches wide, so measure your pet before you decide.
Both models read an approved implanted microchip or RFID collar tag on entry and can store up to 32 identities. The Pet Door also has a programmable curfew; the Cat Flap has a four-way manual lock.
SureFlap pet door vs cat flap: which size fits your pet?
The Pet Door has the larger opening and is the better starting point for a small dog or a cat that needs extra room. The Cat Flap is smaller and suits cats that can pass through its opening without squeezing.
The difference is substantial in both directions: the Pet Door opening is 6 11/16 inches high and 7 inches wide, while the Cat Flap opening is 4 3/4 inches high and 5 5/8 inches wide. These are the flap openings, so use them to assess the space your pet must pass through.
Measure your pet across its widest point and from the floor to the top of its back. Then consider how it moves through a doorway: a pet that crouches or turns may need more clearance than its standing width suggests.
Our guide on measuring your pet and doorway explains what to check before you cut or order. If you're still comparing general styles, how to choose a dog door walks through the main fit and access questions.
Is the Cat Flap opening enough for your cat?
The Cat Flap is a reasonable fit when your cat can pass through a 4 3/4 by 5 5/8 inch opening comfortably. Don't assume it will fit just because your cat is small; compare the opening with your cat's body and preferred way of moving.
If the measurements feel close, move up to the Pet Door's larger opening. A little extra space can make daily passage easier, especially for an older, broad or hesitant cat.
Can a small dog use the Pet Door?
The Pet Door is the more suitable of these 2 models for a small dog because its opening is larger and SureFlap describes it for small dog breeds. Still, the opening is only 6 11/16 inches high by 7 inches wide, so check your dog's measurements rather than relying on breed alone.
For a dog that needs a larger opening, compare options in our guide to dog doors for small dogs and toy breeds. That guide can help you decide whether a microchip cat door is the right type at all.
Do both SureFlap doors recognize the same microchips?
Both models support 9-digit Avid Secure, 10-digit FDXA and 15-digit FDXB microchip numbers. If you don't know your pet's number, ask your veterinarian, shelter or rescue organization.
Each model learns up to 32 identities and scans on entry. That helps keep unrecognized animals from entering while allowing an enrolled pet through without a collar tag.
The Pet Door includes one RFID collar tag, while tags for pets without implanted microchips are sold separately according to its feature details. The Cat Flap's feature details say programmable collar tags are sold separately for cats without microchips.
Neither model blocks an animal from leaving when entry is restricted. Keep that detail in mind if you need to control both entry and exit.
Our microchip cat door guide compares this access style with other choices. You can also read our SureFlap vs Cat Mate comparison if brand choice is your next question.
Which model gives you more control over access?
Choose the Pet Door if you want a timed curfew; choose the Cat Flap if you want a four-way manual lock. Both scan approved identities on entry, but their extra controls differ.
The Pet Door lets you program a time for the door to lock and open. Its feature description also says any animal can exit when entry is restricted, so the schedule controls access in one direction.
The Cat Flap's four-way manual lock lets you set combinations of in and out access. That can be useful when you want to lock the flap manually, but it doesn't provide the Pet Door's scheduled curfew.
Think about your routine. A timed schedule may suit a household that wants a consistent overnight lock, while a manual setting may suit someone who prefers to change access as needed.
What installation and battery differences should you expect?
Both models can be installed in a door, window or wall, and both run on 4 alkaline batteries. The Pet Door uses C batteries; the Cat Flap uses AA batteries.
The Pet Door's battery life is estimated at up to 12 months depending on use. The Cat Flap also has an estimated life of up to 12 months with normal use, and both have a low battery indicator.
Glass or wall installation may need additional parts. The Pet Door's description calls for a mounting adaptor for glass and an adaptor plus one or more tunnel extenders for walls; check the installation requirements for the exact model and surface.
Before buying either one, check the opening location and the material you plan to cut. A door, window and wall installation can need different parts and effort.
If your goal is a pet door in a sliding glass setup, see our guide to sliding glass pet door inserts. For brick, our article on installing a dog door in a brick wall covers the extra planning that wall work needs.
Which SureFlap model should you choose?
Pick the Pet Door for a larger opening, small dog use or a programmable curfew; pick the Cat Flap for a cat-sized opening and manual lock choices. Measure first, because the opening size is the deciding factor for most pets.
Choose the Pet Door when the Cat Flap opening would be tight or when you need to accommodate a small dog. Choose the Cat Flap when your cat fits its smaller opening and you value its four-way manual lock.
For a cat that fits both, decide whether a timed curfew or the smaller flap better matches your home. For broader options and advice, browse our automatic pet door guide.
Sources and product scores
We compared the listed opening sizes, access controls, battery types and installation notes against the needs behind this search. Our scores weigh those features against the likely fit for a cat or small dog.
External product details: SureFlap Microchip Pet Door and SureFlap Microchip Cat Flap.
Frequently asked questions
Is the SureFlap Pet Door bigger than the Cat Flap?
Yes. The Microchip Pet Door opening is 6 11/16 inches high by 7 inches wide, while the Cat Flap opening is 4 3/4 inches high by 5 5/8 inches wide.
Measure your pet at its widest and tallest points, then compare those measurements with the flap opening.
Can a small dog use the SureFlap Cat Flap?
The Cat Flap has a 4 3/4 by 5 5/8 inch opening, so it suits only a dog that can comfortably pass through that space. The Pet Door is larger at 6 11/16 by 7 inches and is described for small dog breeds, but measure your dog before choosing.
Do both SureFlap doors keep stray cats from entering?
Both models scan an implanted microchip or compatible RFID collar tag on entry and can store up to 32 identities. Their selective entry feature helps prevent unrecognized animals from coming in, but any animal can exit when entry is restricted.
What batteries do the SureFlap models use?
The Microchip Pet Door uses 4 C alkaline batteries, and the Cat Flap uses 4 AA alkaline batteries. Neither set is included, and both models have a low battery indicator.
Battery life is estimated at up to 12 months depending on use.
