The short answer
For a QR code that people scan up close, such as on a business card, a product label or a menu, print it at least 2 × 2 cm (0.8 × 0.8 in). For anything scanned from further away, make the code about one tenth of the scanning distance: 10 cm wide for a poster read from 1 meter, 30 cm for a shop window read from 3 meters.
Those two numbers cover most situations. The rest of this guide explains when to go bigger, why, and how to avoid the mistakes that make printed codes fail.
Why size matters
A phone camera has to see each individual square of the code, called a module, clearly enough to tell dark from light. When modules get too small for the distance, the camera blurs neighbouring modules together and the decoder gives up. People rarely try twice. They assume the code is broken and walk on.
Size is not about pixels. A 4000-pixel image printed 1 cm wide is still a 1 cm code. What counts is the printed width compared with the distance between the code and the phone.
The 10:1 rule, explained
The most widely quoted guideline is a 10:1 ratio of scanning distance to code width. It assumes a fairly simple code: around 25 to 29 modules per side, which is what you get from a short link. The ratio comes from the resolution of typical phone cameras and how wide their field of view is at a given distance.
| Scanning distance | Minimum code width |
|---|---|
| 20 cm (8 in) | 2 cm (0.8 in) |
| 50 cm (20 in) | 5 cm (2 in) |
| 1 m (3.3 ft) | 10 cm (4 in) |
| 2 m (6.6 ft) | 20 cm (8 in) |
| 5 m (16 ft) | 50 cm (20 in) |
| 10 m (33 ft) | 1 m (39 in) |
Treat these as minimums under decent conditions. If people will scan at an angle, in dim light, or from a moving vehicle, add 25–50%.
More data needs a bigger code
Every QR code has a version between 1 and 40. Version 1 is 21 × 21 modules; each version adds 4 modules per side, so version 10 is 57 × 57 and version 40 is 177 × 177. The version is chosen automatically from the amount of data and the error correction level.
At the same printed width, a version-10 code has modules roughly half the size of a version-3 code. To keep them readable, the code has to grow in proportion. Some examples:
| Content | Approx. bytes | Version (level M) | Modules |
|---|---|---|---|
| Short link (example.com/menu) | 24 | 2 | 25 × 25 |
| WiFi login | 45 | 3–4 | 29–33 |
| Long tracking link | 120 | 6 | 41 × 41 |
| vCard with address | 330 | 10–11 | 57–61 |
Our QR code size calculator estimates the version from your exact content and adjusts the minimum size for you. The simplest way to make a code smaller is to put less in it: use a short link on your own domain, remove tracking parameters you don't need, or leave optional vCard fields empty.
Error correction and logos
QR codes can repair themselves. Error correction level L recovers about 7% damage, M 15%, Q 25% and H 30%. Higher levels store more redundant data, which means more modules.
If you put a logo in the middle of the code, you need level H, because the logo hides real data. That usually bumps the code up a version or two, so plan for a slightly bigger print. Keep the logo below roughly a quarter of the code area; the larger it is, the less margin is left for scratches, glare and bad lighting.
Don't forget the quiet zone
Around every QR code there must be an empty margin called the quiet zone. The QR standard asks for four modules on each side. Scanners use it to find the edges of the code. If text, a border or the edge of the page runs right up to the code, many phones won't recognize it at all.
In practice: if your code is 3 cm wide with 29 modules, each module is about 1 mm, so leave at least 4 mm of clear space on every side. Our generator's margin slider adds this for you. When you place a code in a design tool, treat the margin as part of the code.
Minimum module size
Another way to think about size is the width of a single module. As a rule of thumb, keep modules at least 0.4–0.5 mm wide for close-range scanning. Below about 0.33 mm, even good phones start to struggle, and printing defects (ink spreading, uneven paper) become a real problem. At 0.5 mm, a version-3 code (29 modules) needs about 1.5 cm; a version-10 code (57 modules) needs about 2.9 cm.
Sizes for common print items
| Item | Typical distance | Recommended size |
|---|---|---|
| Business card | 15–25 cm | 2–2.5 cm (0.8–1 in) |
| Product label, packaging | 20–30 cm | 2–3 cm (0.8–1.2 in) |
| Table tent, menu | 30–40 cm | 3–5 cm (1.2–2 in) |
| Flyer, brochure | 30–50 cm | 3–5 cm (1.2–2 in) |
| A4 / Letter poster | 1–2 m | 10–20 cm (4–8 in) |
| Shop window, door | 2–3 m | 20–30 cm (8–12 in) |
| Trade show banner | 3–5 m | 30–50 cm (12–20 in) |
| Billboard | 10 m and more | 1 m or more |
Before you design around these numbers, picture where people will actually stand. A code on a bus shelter is read from the pavement, maybe 1.5 m away; a code on the bus itself is read from 5 m or more, for a few seconds.
Resolution and file formats
For print, the format matters more than the pixel count:
- SVG is a vector format. It stays perfectly sharp at any size and is the best choice for professional printing, signage and large formats.
- PDF is what most print shops ask for. Our generator's PDF places the code on an A4 page; the printable templates produce 300 dpi layouts.
- PNG works fine if the resolution is high enough. Aim for 300 dpi at the printed size: a 5 cm code needs about 600 pixels, a 20 cm code about 2400 pixels.
- JPG is acceptable, but compression can blur the edges of modules. Use maximum quality.
Never enlarge a small PNG you found in an email. Generate the code again at the right size, or download the SVG.
Materials and surfaces
- Matte beats glossy. Glossy paper, laminate and acrylic reflect light straight into the camera. If you must laminate, use a matte laminate.
- Curved surfaces such as bottles and cups distort the code. Keep the code small relative to the curve, or print it on a flat part of the label.
- Textured paper and fabric blur fine detail. Go one size up and use a simple dot style.
- Metallic and foil inks often look dark to us but bright to a camera. Test before you commit.
- Outdoor prints fade. A code that scans in March may be too pale by August. Use UV-resistant inks for long-term outdoor use.
Test before you print the batch
- Upload your final file to the scannability checker, which checks contrast, quiet zone, density and logo size.
- Print one copy at the real size, on the real material.
- Scan it from the real distance with at least two phones, an iPhone and an Android, ideally one of them a few years old.
- Try it in the lighting where it will hang: a dim restaurant, a sunny window.
Ten minutes of testing costs nothing. Reprinting 500 menus costs a lot.
Summary
- At least 2 × 2 cm for anything handheld.
- About one tenth of the scanning distance for posters and signs.
- Bigger for long content, logos (level H) and difficult conditions.
- Always keep a four-module quiet zone.
- Use SVG or PDF for print, or PNG at 300 dpi.
- Test a real print before ordering in bulk.
Frequently asked questions
What is the smallest QR code size that works?
Around 2 × 2 cm (0.8 in) is the practical minimum for general use. Smaller codes can work for very short content, but many phones can't focus that close.
How big should a QR code be on a poster?
About one tenth of the distance people will scan from. For 2 meters, print at least 20 cm wide.
What resolution should a QR code be for printing?
300 dpi at the printed size, or use an SVG vector file, which has no resolution limit.