Can your phone scan a pet microchip? What actually works

A pet microchip is a tiny passive transponder about the size of a grain of rice. It has no battery. A scanner held close to it sends out a radio signal on 134.2 kHz, which powers the chip for a moment so it can answer with its number. That frequency is set by the international standard for animal chips, ISO 11784/11785.

The contactless reader in a phone (NFC) works on 13.56 MHz, a hundred times higher. It can't power a pet chip or hear its answer, and no app can change the hardware inside the phone. It's the same reason your phone can't read a car key fob.

Search an app store for a microchip scanner and you'll find plenty. The honest ones are companions for a separate handheld scanner: the scanner does the reading and sends the number to the phone over Bluetooth. Others let you type in a chip number you already have, to see which database it's registered with.

Any app that claims your phone alone can read a chip through a pet's skin is simply wrong, and some are there to show adverts. Don't let one stand between a found pet and a real scanner.

Our guide on where to get a pet microchip scanned has more detail, including what to do out of hours.

• Any vet practice. Scanning a found pet is routine, and vets don't normally charge for it.
• Your local council's dog warden service, for dogs.
• Rescue centres such as Dogs Trust, the RSPCA, Blue Cross and Cats Protection.
• Some groomers, boarding kennels and pet shops keep a scanner too.

The scanner shows a number and nothing else. The vet or warden looks that number up to find which database the chip is registered with, and the database contacts the registered keeper. The finder isn't handed the owner's address, which protects both sides.

It only works if the details on the database are current, and out-of-date details are the most common reason a chipped pet isn't reunited. If you're an owner, check your pet's microchip details now, and see which UK databases there are.

A microchip is the backstop: it works once a pet reaches someone with a scanner. The ID that works in the hands of whoever actually finds a pet is on the collar, where a phone can read it.

• An engraved tag with a phone number: anyone can read it, no phone needed. UK law requires a dog in a public place to wear its owner's name and address in any case.
• A QR code tag: any phone camera opens the pet's page, with a way to reach the owner straight away.
• An NFC tag: works on phones that have NFC switched on, held right against the tag. Our guide on NFC or QR compares the two.

Look for a tag first: a phone number or QR code is the fastest route home. If there's none, a vet or the council can scan for a chip. Our step-by-step guide covers what to do when you find a dog or cat.

If you're an owner reading this, it's why a QR code pet tag is worth having alongside the chip: the person who finds your pet can reach you from their own phone, on the spot, without a trip to the vet.