# QR codes on pet tags

> A pet tag disc is 2–3 cm across, leaving about 1.8 cm for the code, so the payload must stay tiny: a version-3 code at error correction H holds only 24 characters. Engrave a short portal URL rather than a phone number; it survives scratches and stays updatable.

Source: https://useqr.app/qr-codes-on/pet-tags · Last reviewed 2026-08-21 · UseQR is free forever, no signup.

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| Typical scan distance | **10–15 cm** |
|---|---|
| Minimum code width | **1.5–1.8 cm** |
| Error correction | **H** |

## The version budget

A pet tag disc is **2–3 cm** in diameter, and after the rim and the quiet zone the code
gets roughly **1.8 cm**. That is the tightest version budget of any common surface:

| Version | Modules | Module size at 1.8 cm | Capacity at EC H |
|---|---|---|---|
| 2 | 25 | 0.72 mm | 14 characters |
| 3 | 29 | 0.62 mm | 24 characters |
| 4 | 33 | 0.55 mm | 34 characters |

**Version 3 at error correction H holds 24 bytes.** `https://useqr.app/t/x9k2` is exactly
24, a short URL fits and almost nothing else does. A full address or a
[vCard](/vcard-qr-code) forces version 8+, and sub-0.3 mm modules on a scratched disc do
not scan. The [capacity table](/docs/reference/qr-code-capacity-table) has the full grid;
this surface is why [short payloads make better codes](/docs/print/qr-code-size-for-print).

## Wear is the failure mode

A tag lives on a moving animal: it grinds against the collar buckle, gets chewed, swims,
and spends its life under fur. Two consequences:

- **Error correction H, always.** Scratches accumulate for years; 30% recovery capacity
  is the whole survival plan.
- **Fur occlusion** defeats codes more often than damage does. A tag that hangs face-in
  against the chest cannot be scanned by a stranger holding a wriggling dog. Double-sided
  engraving, or a slide-on collar tag that sits flat and face-out, fixes the geometry.

## Production: engraved beats printed

Printed and stickered tags fail in months. The durable options are covered in
[engraved metal](/qr-codes-on/engraved-metal) and
[etched vs printed](/docs/print/qr-codes-etched-vs-printed); for tags specifically:

- **Laser-engraved anodised aluminium**, the laser removes dark anodising to leave light
  metal. Order the geometry so modules end up **dark on light**, not the reverse; an
  inverted code fails many native scanners.
- **Fibre-laser on stainless steel** produces a dark oxide mark on bright metal: durable
  and correctly polarised, but confirm contrast clears the **40% luminance-difference**
  floor at shallow angles, since bare metal reflects.
- Deep-engrave-and-fill (dark epoxy in recessed modules) survives chewing best.

## Put a portal URL on it, not a phone number

Encoding your phone number directly feels obvious and is the worse design:

- **Privacy**: the number is readable by anyone who ever photographs the tag, forever.
- **Updatability**, numbers change; an engraved payload does not. A URL you control can
  [point somewhere new](/docs/how-to/how-to-change-what-a-qr-code-points-to) after a house
  move without re-engraving.
- **Mediation**, a simple pet-profile page can show medical notes and a contact form
  without exposing the number itself.

## FAQ

### How small can a QR code be on a pet tag?

About 1.5 cm is the floor. At 1.8 cm a version-3 code has 0.62 mm modules, which scans at
phone distance; anything denser than version 4 on a disc this size becomes unreliable once
the surface picks up scratches.

### What should the QR code on a pet tag link to?

A short URL pointing at a pet profile page, not a raw phone number. The URL fits the
24-character budget of a version-3 code at error correction H, keeps your number private,
and can be repointed if your details change.

### Do QR code pet tags actually work?

Yes, within limits: the finder needs a smartphone, the tag must hang face-out, and the
engraving must keep dark modules on a light ground. Error correction H covers years of
scratching. Pair the code with an engraved backup phone number if space allows.

### Is engraving or printing better for a pet tag QR code?

Engraving. Printed or stickered codes on a collar tag wear off in months of friction and
weather. Laser-engraved anodised aluminium or filled stainless engraving lasts the life of
the tag, just ensure the result reads dark-on-light.

## Try it

- https://useqr.app/url
- https://useqr.app/phone
- https://useqr.app/size-calculator
- https://useqr.app/validate