The two numbers that decide the size
A QR code scans when the phone's camera can resolve its smallest square — the module — clearly enough to tell black from white. So the size you need depends on two things:
- How far away the phone will be. Further away, each module looks smaller to the camera.
- How much data the code holds. More data means more modules packed into the same square, so each one is smaller.
Most size advice only mentions the first. The second is why a contact-card code printed at the same size as a short-link code can fail where the link works.
The 10:1 rule for distance
The widely used rule of thumb is that a QR code should be one tenth of the scanning distance across.
| Scanning distance | Minimum code width | Typical placement |
|---|---|---|
| 25–30 cm | 2.5–3 cm | Business card, product label, table card |
| 50 cm | 5 cm | Menu, flyer held in hand |
| 1 m | 10 cm | Counter display, shop window at arm's length |
| 2 m | 20 cm | Poster on a wall, event signage |
| 5 m | 50 cm | Large banner, trade show backdrop |
| 10 m | 1 m | Billboard, building signage |
Treat these as minimums for a short, simple code. Below roughly 2 cm, even a tiny code becomes unreliable on older phones, however close the reader holds it.
Why data density changes everything
A QR code's grid grows with the amount of data. The standard defines 40 sizes, called versions. Version 1 is 21 × 21 modules; every version adds four modules per side, up to 177 × 177 at version 40.
These are real figures from the encoder, at the default error correction level M:
| Content | Characters | Version | Grid |
|---|---|---|---|
https://qrfast.io |
17 | 2 | 25 × 25 |
| A 40-character URL | 40 | 3 | 29 × 29 |
| A WiFi network and password | 46 | 4 | 33 × 33 |
| An 80-character URL with tracking tags | 82 | 5 | 37 × 37 |
| A full vCard (name, company, title, phone, email, website) | 208 | 10 | 57 × 57 |
Print the first and last of those at 3 cm and the vCard's modules are less than half the width of the short link's. The vCard code needs more than twice the size to scan equally well.
That is why the generator shows the version and module count under the preview — it is the information you actually need to choose a print size.
A better rule: size each module
For anything denser than a short link, size the code from its modules rather than its overall width. Our engineering rule of thumb, which matches the 10:1 rule for typical short-link codes:
Each module should be at least 1/350th of the scanning distance, and never smaller than about 0.4 mm.
Then add the four-module quiet zone on each side. The minimum width is:
(modules per side + 8) × distance ÷ 350
| Code | Modules + quiet zone | At 30 cm | At 1 m | At 3 m |
|---|---|---|---|---|
| Version 2 (short link) | 33 | 2.8 cm | 9.4 cm | 28 cm |
| Version 4 (WiFi) | 41 | 3.5 cm | 11.7 cm | 35 cm |
| Version 7 | 53 | 4.5 cm | 15.1 cm | 45 cm |
| Version 10 (full vCard) | 65 | 5.6 cm | 18.6 cm | 56 cm |
| Version 15 | 85 | 7.3 cm | 24.3 cm | 73 cm |
If those numbers are bigger than you have space for, reduce the data rather than the margin of safety: shorten the URL, remove tracking parameters, or put a short link in the code and let the web page carry the detail.
Minimum sizes by use
| Use | Practical minimum | Notes |
|---|---|---|
| Business card | 2 cm (short link), 2.5–3 cm (vCard) | Prefer a short URL to a full vCard if space is tight |
| Product packaging | 2–2.5 cm | Curved surfaces: add 20% and keep the code off the curve's edge |
| Restaurant table card | 3–4 cm | Low light; use high contrast and matte finish |
| Menu or flyer | 3 cm | |
| A4 poster | 8–10 cm | Readers stand about a metre away |
| A1 poster or shop window | 15–20 cm | |
| Billboard | 1 m+ | Use a very short URL to keep the version low |
Things that matter as much as size
The quiet zone. The four modules of blank margin around the code are part of the symbol. Cropping them to fit a layout is one of the most common causes of failure. Our downloads include the quiet zone; leave it in.
Contrast. A dark code on a light background, with strong contrast. Light-on-dark codes fail on many scanners. See the design guide.
Error correction. Higher levels make the code denser. If you raise it from M to H for durability, check the version again and resize — the error correction guide has capacity tables.
Finish. Glossy lamination under bright lights creates glare that wipes out part of the code. Matte finishes scan reliably.
Angle and curvature. A code on a bottle or a cup curves away from the camera at its edges. Keep it small relative to the curve, or place it on a flat label.
Test like it is going to fail
Print a proof at final size on the final material, then scan it from the real distance in the real lighting with at least one iPhone and one Android phone, including an older model if you can find one. It costs a few minutes and saves reprinting the whole run.
Frequently asked questions
What is the minimum size for a QR code?
About 2 × 2 cm for a short, simple code scanned from close range. Codes carrying more data, such as a full contact card, need 2.5–3 cm or more at the same distance because their modules are smaller.
How big should a QR code be on a poster?
Use the 10:1 rule: one tenth of the distance people will stand from it. For a poster read from 2 metres, that is about 20 cm across. Keep the encoded URL short so the code stays low-density.
How big should a QR code be on a business card?
At least 2 cm for a short URL. A full vCard code is much denser and needs 2.5–3 cm; if you cannot spare the space, encode a short link to an online contact page instead.
Does the size of the QR code affect how much data it can hold?
No — capacity depends on the version (the number of modules), not the physical size. But more data means more, smaller modules, so a code holding more data must be printed larger to scan from the same distance.
Can a QR code be too big?
Only in the sense that the whole code must fit in the camera's view. Very large codes read from close range can fail because the phone cannot frame them; size for the actual viewing distance.
What resolution should I export for print?
Use SVG wherever possible; it is resolution-independent. If you need a PNG, export at 2048 pixels or more, which gives over 300 dpi for codes up to about 17 cm wide.
Further reading
- Do QR codes expire? — A QR code itself never expires — but a dynamic code can die when a subscription ends. How to tell which kind you have, and how to get an editable code without the risk.
- GS1 Digital Link: QR codes on products, explained — How GS1 Digital Link puts a product's GTIN, batch and expiry into a QR code that both checkouts and phones can read, what Sunrise 2027 means for brands, and how to build one correctly.
- How QR codes work, from pattern to payload — A clear technical walkthrough of a QR code: the finder and timing patterns, how text becomes bits in each encoding mode, Reed–Solomon error correction, masking, and how a phone reads it.
- How to scan a QR code on any device — Scan QR codes with the built-in camera on iPhone and Android, from a screenshot or photo, on a Windows or Mac computer — and what to do when a code will not scan.