Most printed QR codes that fail are simply too small. Not by a little — by half. The good news is that the sizing question has a single rule behind it, and everything else is applying that rule to a particular job.
The rule
A QR code should be about one tenth as wide as the distance it will be scanned from.
Scan from 30 cm, print at 3 cm. Scan from 2 metres, print at 20 cm. It is a rule of thumb rather than a standard, but it matches how phone cameras actually behave and it has the useful property of being easy to do in your head.
Underneath it sits a hard floor: do not print below 2 × 2 cm for anything, no matter how close it will be held.
Sizes by job
| Job | Scanned from | Minimum size |
|---|---|---|
| Business card | 20-25 cm | 2 cm |
| Product label, receipt footer | 20-25 cm | 2 cm |
| Flyer, A5 leaflet | 30 cm | 3 cm |
| Table tent, menu card | 40-50 cm | 4-5 cm |
| A4 poster on a wall | 60-80 cm | 6-8 cm |
| Counter or till sign | 50 cm | 5 cm |
| Shop window | 1-2 m | 10-20 cm |
| Roll-up banner | 2-3 m | 20-30 cm |
| Vehicle livery | 3-5 m | 30-50 cm |
| Billboard | 20 m+ | 2 m+ |
These are minimums. Going bigger costs nothing but layout space and always improves reliability.
Density changes the answer
Two codes at the same physical size are not equally readable. The more data you encode, the more modules the pattern needs, and the smaller each one gets.
A short link might produce a 25-module code; a full vCard with an address can push past 40. At 2 cm that is the difference between 0.8 mm and 0.5 mm per module — and 0.5 mm is where cheap cameras and cheap printing start to fail together.
So there are two ways to fix a code that is too small for its space: make it bigger, or make it carry less. Shortening a long URL is often the easier of the two.
Getting the file resolution right
Physical size is only half of it. The file has to have enough pixels to print sharply at that size.
At the 300 DPI commercial printers assume:
| Download size | Prints sharp up to |
|---|---|
| 512 × 512 px | about 4 cm |
| 1024 × 1024 px | about 8.5 cm |
| 2048 × 2048 px | about 17 cm |
Anything larger than a poster should use the SVG instead, which stays sharp at any size. Our PNG vs SVG guide covers the choice.
Do not forget the margin
The size in the table is the code itself. It still needs its quiet zone around it — roughly another sixth of the width on every side. Budget for that in the layout rather than discovering it at the end and cropping.
Things that mean you should size up
- The code will be read outdoors, or through glass
- The surface is glossy, curved or textured
- Your audience skews towards older or budget Android phones
- The code carries a lot of data
- It has a logo in the middle
- It will be printed on uncoated or coloured stock
Any two of these together, add 50% to the minimum.
Check it physically
Print one at the intended size, on the intended material, and scan it from where a real person will stand. Not from the screen, not from a nice A4 test print of a sign that will actually be vinyl.
The pre-print checklist has the whole routine. Ten minutes there is cheaper than a reprint.
Make your code and pick the download size to match the job.