The short answer
Microchip doors read the chip already in your pet and unlock only for registered pets. SureFlap states it reads all common microchips (or an included RFID tag) and stores 32 pets; PetSafe SmartDoor reads FDX-B, FDX-A and AVID chips on its Medium size only. Most microchip doors suit cats and small dogs; many read only on entry.
Chip compatibility
| Door | Chips / keys | Pet size |
|---|---|---|
| SureFlap Microchip Pet Door | Common microchips or RFID tag; 32 pets | Large cats and small dogs |
| PetSafe SmartDoor Connected | Collar key, or microchip on Medium only (FDX-B, FDX-A, AVID) | Medium to 25 lb; Large to 100 lb with key |
Entry-only readers
SureFlap reads chips only on the outside, so any animal inside can leave. That's fine for keeping strays out but won't keep one pet in.
Bigger dogs
For large dogs, collar-key or powered doors such as PetSafe Electronic Pet Door or Power Pet PX-2 offer selective entry.
Products mentioned
Questions readers ask
Will a microchip door read my dog's chip?
SureFlap states it reads all common chips; PetSafe SmartDoor reads several standards on its Medium size.
Can a big dog use a microchip door?
Most suit smaller pets; use a collar-key or powered door for big dogs.