What size should a printed QR code be?

A QR code that scans instantly on your monitor can be completely dead on a printed flyer. Almost every time, the cause is the same: the code was sized for the layout instead of for the distance it will be read from.

The 10:1 rule

The working rule is that a QR code should be about one tenth of the distance it is scanned from. It comes out of the module size a phone camera can resolve, and it holds well from a business card to a billboard.

Treat these as floors, not targets. Scanning happens in bad light, at an angle, through a smudged lens, by someone holding a phone one-handed. Adding 20–30% on top of the minimum costs almost nothing and removes most of the failures.

Why the module, not the code, is the real unit

A QR code is a grid of modules — the little squares. A “version 3” code is 29 modules across; a version 10 is 57. If you keep the printed size fixed and add more data, each module gets smaller, and at some point it drops under what a camera can separate from its neighbours.

The practical minimum for offset or digital print is roughly 0.4 mm per module; for thermal labels and anything on a rough surface, closer to 0.6 mm. Multiply by the module count and you get the honest minimum size:

• 29 modules × 0.4 mm ≈ 1.2 cm
• 57 modules × 0.4 mm ≈ 2.3 cm
• 77 modules × 0.4 mm ≈ 3.1 cm

This is why shortening the encoded URL is a print decision, not just a tidiness one. https://example.com/s/4f2 is a much smaller code than the same link with four UTM parameters bolted on, and it will scan from twice the distance at the same physical size.

The quiet zone is part of the code

The specification requires four modules of blank margin on all four sides. It is not decoration — the decoder uses it to find the symbol’s edges. A code pushed flush against a coloured panel, a photo or the trim line of a page loses that boundary, and many readers simply never lock on.

If your layout is tight, shrink the code and keep the quiet zone. A smaller code with a correct margin beats a bigger one without.

Error correction changes the maths

Raising error correction from L to H adds redundancy, which adds modules, which shrinks each module at the print size you already committed to — so choosing H and keeping the code small is the worst of both worlds. M is the right default for clean print on paper; go higher only when you can name the thing that will obscure the symbol. What L, M, Q and H really cost you prices every level in versions, modules and millimetres, including the case where the higher level is free.

Material and finish matter more than people expect

• Matte beats gloss. A glossy varnish throws a highlight straight back at the camera and blows out half the symbol.
• Never print a code across a fold or a seam. The fold line reads as a break in the modules.
• Curved surfaces (cans, bottles, tubes) need a smaller code on a flatter part of the surface, or a higher error correction level to survive the distortion.
• Dark ink on a light background, not the reverse. Most decoders assume it, and although many handle inversion, “most” is not “all”.

Test before you print a thousand of them

Print one copy at final size on the final stock, and scan it with a cheap Android phone, in the light the code will actually live in, from the distance a real person will stand at. That single test catches nearly every problem on this page — and it is the one step that gets skipped.

Ready to make the code? The generator runs in your browser: paste the URL, pick the error correction level this page recommended, and export SVG if it is going to print, because vector stays sharp at any size.