Why a QR code behaves differently on paper than on screen
A QR code that looks sharp on a monitor can still become unreadable on a printed flyer if it is printed too small or lacks contrast on matte paper. A phone camera has to pick the code up from a certain distance, unlike scanning straight off a screen.
Create QR code generates the code at high resolution, so it stays sharp in print instead of turning pixelated.
How big it needs to be on paper
As a rough rule, the further the viewer stands from the code, the bigger it needs to be. On a business card scanned from a few centimetres away, a code around two centimetres per side is enough. On a poster meant to be scanned from a metre away, the code needs considerably more surface area.
Contrast beats colour
A coloured QR code looks nicer on a flyer, but only works if the contrast between the modules and the background stays high enough. Dark blue on white usually reads fine, a light yellow on white barely does. When in doubt, plain black on white remains the safest choice.
Link, vCard or Wi-Fi: what belongs in the code
On a flyer meant to point at a website, a plain link is enough. On a business card, a vCard is often the better choice, since the contact lands straight in the address book instead of just opening a web page.
A margin that should never be skipped
A QR code needs a calm, empty margin all around it so the camera can pick up the whole pattern at once. Printing the code right at the edge of the flyer, or letting text overlap it, can make scanning fail even when the code itself is technically correct.
Testing before the print run
A test print on ordinary paper, scanned with two or three different phones, shows far more reliably than any screen preview whether the code actually works at the planned size.
Common questions
Does a QR code expire at some point? No, a static code with fixed content stays valid indefinitely.
Can the content be changed afterwards? Not with a simple code, the content is fixed into the pattern itself. Changing it means generating a new code.
How wide should the margin around the code be at minimum? A useful rule of thumb is about four modules of the code's own pattern.