When Can a Puppy Wear an ID Tag? Size, Fit and What to Engrave

Last updated: December 2025

When can a puppy start wearing an ID tag?

Your puppy can wear an ID tag as soon as it can comfortably wear a collar, which for most puppies means the day they come home. Trainers quoted by Rover say a puppy can start wearing a collar as early as eight weeks. Battersea Dogs and Cats Home says collar training can start as soon as your puppy comes home.

The early weeks are exactly when a tag matters most. A new puppy does not know your house, your street or its own name yet. Hill’s Pet Nutrition puts it plainly: your puppy can easily get lost, especially in its early weeks, so attach an ID tag with your name and contact information.

The research backs that up. In a 2007 study of 187 lost dogs in Montgomery County, Ohio, Linda Lord and colleagues found that 47 of the dogs were a year old or younger, and 62 had been owned for a year or less. Only 19% of the lost dogs were wearing a personal ID tag.

American Humane says all puppies and dogs should wear collars and ID tags, and notes that in many areas it is the law. If you are still gathering supplies, our new puppy checklist puts the collar and tag on the list for day one, not week six.

How should a puppy collar fit with a tag on it?

A puppy collar should fit snugly enough that it cannot slide over the head, but loosely enough that you can slip two flat fingers between the collar and the neck. This is the two-finger rule, and nearly every animal welfare group uses it. The International Welfare Collar Trust describes it as fitting your index and middle finger, without force, under the collar.

American Humane allows a little more room, saying you should be able to easily slip two or three fingers under the collar.

To size a first collar, measure the neck with a soft tape. The International Welfare Collar Trust suggests adding 1 inch for small dogs, 2 inches for standard dogs and 3 inches for large dogs, and buying a collar that hits that length on the middle hole. That middle setting leaves room to let it out as your puppy grows.

A few fit details matter more with a tag attached:

• Use a flat buckle or snap collar. Hill’s says a puppy’s first collar should have a buckle or snap closure and never be a chain or choke collar.
• Keep the attachment short. One ring straight to the collar’s D-ring swings less and snags less than a chain of rings.
• Do not use a training collar as the tag collar. American Humane warns that head halters, choke chains and prong collars should never be left on an unattended dog.

How often should you check a growing puppy’s collar and tag?

Check a growing puppy’s collar at least once a week. American Humane says to check every week until your puppy is full grown, which can take more than a year for large breeds. Hill’s goes further and suggests checking the size every few days, since puppies can grow quickly in a short time.

This matters because a collar does not grow with the dog. American Humane warns that a collar that is not loosened can literally grow into a puppy’s neck. The International Welfare Collar Trust notes that puppies may need several collars before they are fully grown.

The table below lines up what is happening in your puppy’s body (sourced) with our suggested check schedule and tag moves (our guidance, not a veterinary standard).

How heavy should a puppy’s ID tag be?

A puppy’s ID tag should be as light as possible while still showing your phone number in text a stranger can read at arm’s length. We could not find a veterinary standard that sets a gram limit for pet tags, so the numbers below are our own math, not a medical rule.

Material makes the biggest difference. Engineering ToolBox lists acrylic at about 1.19 grams per cubic centimeter, aluminum at 2.7, steel at 7.82 and brass at 8.4 to 8.75. That means a tag of the same size and thickness weighs roughly six to seven times more in steel or brass than in acrylic.

Real tags vary. Metal tags are often thinner than 2 mm, and acrylic tags are often thicker, so the gap in the real world is usually smaller than this table shows. Rings, charms and a second tag all add weight too.

Those percentages look tiny, but a puppy carries the tag every waking minute, and it swings into the chest with every bounce. A 0.6% load on a 150-pound adult would be almost a pound hanging from a necklace all day.

What should you engrave on a puppy’s first ID tag?

Engrave your cell phone number first, then your puppy’s name, and stop there unless you have room to keep the text big. A first tag is not the place for a paragraph. The person who finds your puppy may be standing in the rain, holding a wriggling animal with one hand, reading the tag with the other. Large, clear numbers win.

The two must-haves

• Your cell phone number. This is the line that brings a puppy home. Include the area code, and use the number you actually answer, not a landline that rings in an empty house.
• Your puppy’s name. It helps a finder calm and call the puppy. If the name is long, a short nickname keeps the font larger.

Helpful extras if they fit

• A second phone number. A partner, parent or close friend who can answer when you cannot.
• “Microchipped.” This one word tells a finder or a shelter worker to scan. It only helps if the chip is registered to you, which we cover below.
• City or town. It tells a finder whether the puppy is local or far from home.
• A short medical note. “Needs meds” or “Diabetic” can make a finder act faster.

What to leave off for now

Skip a full street address on a small tag. It eats up space and shrinks the phone number, and a phone call gets your puppy home faster than a stranger driving to your house. Skip jokes and long phrases on the first tag, too.

If your puppy’s name is not final yet

Plenty of new owners spend the first week trying out names. That is no reason to wait on a tag. Order a tag with your phone number in large text and leave the name off, or use a simple placeholder like “Puppy.” A tag with a working phone number and no name is far more useful than a perfect name tag that arrives in three weeks. If the puppy came from a breeder or rescue that asks to be called if the dog is ever found, you can add that number as your second line.

Puppies change phones too

The most common reason a found pet does not make it home is bad contact information, not a missing tag. In the 2009 microchip study by Lord and colleagues, an incorrect or disconnected phone number was the top reason shelters could not find an owner, at 35.4% of cases. The same thing happens to engraved tags. If you move or change numbers during your puppy’s first year, a new tag goes on the to-do list the same day.

Where a smart tag fits

An engraved tag can only hold what fits in a square inch or two. An NFC smart tag lets a finder tap the tag with a phone and open a profile with far more detail, such as several contacts, medical notes and behavior notes. It also means you can update your number without ordering a new tag. Many owners use both: a phone number engraved on the front, and the tap profile for everything else. Our full list of what to include is in what to put on a dog ID tag.

Will a teething puppy chew its ID tag?

Yes, many teething puppies will chew a dangling tag, especially between about 3 and 6 months old. VCA Animal Hospitals explains that puppies have 28 baby teeth, that the baby teeth start to fall out at around 12 weeks, and that by about six months all the permanent teeth have usually come in. During that window, anything near the mouth is fair game, including a littermate’s tag.

Check the tag during your weekly collar check. Look for bite marks, cracks, sharp edges and a bent or opened ring, especially if your puppy plays with other dogs or gets hold of the collar when it is off.

Hard metal is not automatically safer. A tag that does not dent can be rough on a puppy’s teeth, and a chewed plastic tag can leave a sharp edge. Whatever the material, a damaged tag should come off and be replaced.

Collars and tags also carry a snag risk. The Animal Health Foundation warns that dangling tags can catch on crate wires and heater vents, and that playing dogs can get tangled in each other’s collars. For more on the trade-offs of taking a collar off at night, see should you take your dog’s collar off at night.

For the chewing itself, our guide on how to stop puppy biting covers redirection and the right chew toys.

Which is best for a puppy, an acrylic, metal or silicone tag?

For most puppies, a light acrylic or silicone tag is the most comfortable choice, and a metal tag is a fine choice for bigger, older puppies who do not mind the jingle. Each material has a trade-off.

• Acrylic is light, quiet and can be engraved in bold, high-contrast text. It is not chew-proof.
• Silicone is soft and quiet and often slides onto the collar so nothing dangles. Text can be smaller, and soft material can tear.
• Metal is tough and classic, but heavier and noisier, and stamped text can wear down over time.

Slide-on tags sit flat against the collar, which removes most of the snag and swing problem. The catch for puppies is that slide-on tags fit one collar width, and you may go through two or three collar sizes in the first year. A hanging tag moves from collar to collar with one ring.

We compare materials in depth in silicone vs acrylic pet tags and acrylic vs metal dog tags.

Does a puppy need a microchip if it has an ID tag?

Yes. A tag is the fastest way home, and a microchip is the backup when the collar comes off. VCA says most puppies can be microchipped by 8 weeks old, though a very small puppy, like a tiny Chihuahua, may do better waiting until 3 to 4 months.

A chip only works if a shelter or vet scans it and the registry has your current details. In a 2009 study of 7,704 microchipped animals at 53 U.S. shelters, microchipped stray dogs went home 52.2% of the time, compared with a 21.9% overall return rate for stray dogs. But only 58.1% of the chips that shelters looked up were registered in a database.

A tag works in a different way. Anyone with a phone can use it, right where they find the dog. In a 2012 national survey led by the ASPCA, 15% of owners who found their lost dog said they got the call because of a tag or microchip.

“It also highlights the importance of ID tags and other forms of identification to ensure the quick return of lost pets.”

Dr. Emily Weiss, vice president of shelter research and development, ASPCA (2012)

Register the chip the week your puppy gets it, under your name, not the breeder’s or the shelter’s. Our guide to microchip vs smart tag explains how the two work together.

When should you switch your puppy to a bigger tag?

Switch to an adult tag when your puppy has mostly stopped growing, or sooner if the tag looks lost in the fur, is hard to read or no longer suits the collar. The AKC’s chief veterinarian, Dr. Jerry Klein, says small breeds typically stop growing by 6 to 8 months, while giant breeds grow until 12 to 18 months, and some, like Mastiffs, until 24 months.

Signs it is time for a change:

• You have moved up a collar size and the old tag looks tiny.
• A thick coat is hiding the tag.
• The engraving is worn, or your contact details have changed.
• The ring is bent, or the tag has chew damage.

A tag that is a bit small for a big dog is still far better than no tag.

Bringing home a holiday puppy, what ID does it need?

A holiday puppy needs the same ID as any puppy, ready before it walks through the door: a fitted collar, a tag with your phone number and a microchip you have registered. The holidays just make that harder, with guests, open doors and wrapping paper everywhere.

Puppies make good gifts when the person truly wants one. A 2013 ASPCA study found that 96% of people who received a pet as a gift said it either increased or had no effect on their love for the pet, and 86% of those pets were still in the home. The ASPCA recommends pets as gifts only for people who have shown a sustained interest and can care for one.

Set up the tag profile before the big day, too. The free Lohji app holds your puppy’s safety profile at no cost: breed, birthday, medical and behavioral notes, your veterinarian and up to three emergency contacts that a finder can call, text, email or map in one tap. You can record how to say your puppy’s name and up to three 15-second voice messages. Paired with a Smart Tag, the profile opens in the finder’s browser, with no app needed on their end, and any change you make shows up right away. The app also turns a photo into a cartoon “Lohji,” with holiday stickers for Christmas, Hanukkah and New Year’s Eve. Get it on the App Store or Google Play.

Raising a puppy who will grow into a big dog? Our guide to the best ID tags for large dogs explains tag size by weight, ring strength and snag-safe setups for strong, active dogs.

Teething puppies love to mouth their tags. Our guide to chew-proof dog tags explains why no hanging tag is truly chew-proof, which ID setups hold up best and when a chewed tag needs replacing.

Frequently asked questions

Sources

• Journal of the American Veterinary Medical Association — Search and Identification Methods That Owners Use to Find a Lost Dog (2007)
• Journal of the American Veterinary Medical Association — Characterization of Animals With Microchips Entering Animal Shelters (2009)
• ASPCA — How Many Pets Are Lost? How Many Find Their Way Home? (2012)
• ASPCA — It’s Okay to Give Pets as Gifts. Really. (2013)
• American Humane — Choosing a Dog Collar (2016)
• Hill’s Pet Nutrition — Collars, Leashes and ID Tag Tips for New Puppies (2025)
• International Welfare Collar Trust — Collar Fitting Guide
• VCA Animal Hospitals — Teeth, Teething and Chewing in Puppies
• American Kennel Club — When Do Dogs Stop Growing? (2021)
• Engineering ToolBox — Solids Densities