Microchipping Your Cat: How It Works, Cost, and the Law

A cat microchip is a permanent, rice-grain-sized identity chip placed under the skin that links your cat to your contact details on a database, so a lost cat can be scanned and returned to you. It is not a tracker and has no battery; it simply holds a unique number that a vet, rescue, or warden looks up. For most owners it is the single most reliable way to prove a cat is theirs and to get a missing cat home.

This article sits within our new kitten guide and explains why to chip, how it works, what it costs, why the details matter as much as the chip, and where it is now the law.

Why microchip your cat

A microchip is permanent identification that a collar can never match. Collars slip off, break on purpose (quick-release safety collars are designed to), or get pulled off in a fight, but a chip stays put for life. International Cat Care notes that a microchip provides lifelong identification because, unlike a collar and tag, it cannot fall off or be removed. That matters because cats roam: indoor cats bolt through open doors, and an estimated 1 in 3 pets goes missing at some point in its life. A scanned chip with current details turns a stray in a shelter back into your cat in minutes.

I learned the value of this the hard way. When my tabby slipped out during building work and turned up four streets away nine days later, it was the chip, not his looks, that got him back: a neighbour took him to a vet, the scanner read the number, and the database had my phone on it. Without that, he would have been logged as a stray.

How a cat microchip works

A microchip is a passive transponder: it does nothing until a scanner activates it. The chip itself is about 12 mm long, roughly the size of a grain of rice, and sits in a tiny glass capsule. When a handheld scanner is passed over the cat, it powers the chip by radio and reads back a unique 15-digit number (the ISO standard used across most of the world). That number is then looked up on a registration database to find your details. The chip stores no medical history and no GPS location; it is an ID number and nothing more. Because it has no battery, it lasts the cat’s lifetime and never needs charging or replacing.

Getting your cat chipped: the procedure

Chipping is a quick, awake procedure done in an ordinary consultation. A vet or trained implanter loads the chip into a single-use applicator and injects it under the loose skin between the shoulder blades, the same spot used the world over. It takes a few seconds and needs no anaesthetic; most cats react about as much as they do to a routine vaccination. The American Animal Hospital Association and ASPCA both treat it as a standard, low-risk procedure, with complications such as chip migration or local reaction being uncommon. Kittens are often chipped from around 8 weeks, and it is frequently done at the same visit as a vaccination or neutering, which from about 4 months is a natural moment to combine the two.

What microchipping costs

Microchipping is one of the cheaper things you will ever do for your cat. On its own it commonly costs about 10 to 30 pounds, and it is often free or heavily discounted when bundled with another visit: many rescues chip every cat before rehoming, and charity neutering schemes frequently include the chip in the price. Set against the wider cost of cat ownership, it is a rounding error; our guide to how much a vet costs puts it in context against vaccinations, parasite control, and the bigger bills. Updating your details later is usually free or a few pounds.

Keeping your details up to date

A microchip is only as good as the details attached to it. The chip number is registered on a database (in the UK there are several approved ones) alongside your name, address, and phone number, and that record is what actually reunites you with your cat. If you move house, change your phone number, or rehome the cat and do not update the record, the chip leads to a dead end. This is the step owners forget: a chipped cat with a stale phone number is, in practice, no better off than an unchipped one. Whenever your contact details change, log in to your database and update them, and check the record after rehoming a rescue so it points to you, not the previous keeper.

The law on microchipping cats

In some regions microchipping a cat is now a legal duty, not just good practice. In England, the Microchipping of Cats and Dogs (England) Regulations 2021 made it compulsory to microchip pet cats over 20 weeks old from 10 June 2024, with their details kept on a compliant database; owners who fail to comply can be given 21 days to chip the cat or face a fine of up to 500 pounds. Rules vary elsewhere: many countries and US states recommend rather than require chipping, and some mandate it only for imported or licensed animals. Even where it is optional, welfare bodies including the RSPCA and International Cat Care advise it for every cat, because it is the most dependable route home. As part of responsible ownership it pairs naturally with microchipping decisions in the new kitten guide and routine preventive care.

This guide is general information, not a substitute for professional advice. For your cat’s chipping, the procedure, and your local legal requirement, speak to your own vet, who can scan, implant, and advise based on where you live.