QR codes that still work in two years
A printed QR code is the least editable thing your company produces. Ten thousand of them on conference badges commit you to whatever URL was correct the week the file went to the printer. There is one decision that makes them survivable, and it is made before printing.
Encode a short link, never the destination
A QR code encoding your final URL is permanent in the worst sense. Restructure the site, move the campaign page, change domain after an acquisition, and every printed code becomes a 404 you cannot recall.
Encode a short link instead and the printed artefact points at something you control. The destination becomes an editable field. This is the entire reason QR codes and shorteners are usually sold together, and it is a genuinely good reason rather than a bundling trick.
badge, poster, flyer. You can then retarget the badge without touching the poster, and the scan counts stay separable.Shorter URLs make better codes, physically
This is not a metaphor. More encoded characters means a higher QR version, which means more modules in the same square, which means each module is physically smaller at a fixed print size. Smaller modules are harder for a camera to resolve, particularly at an angle, in poor light, or on a curved surface.
A URL with UTM parameters attached can easily exceed a hundred characters. The equivalent short link is around twenty. The short version scans from further away, tolerates worse printing and survives being placed on a coffee cup. Keep the tagging on the destination, where it does not have to be photographed.
Error correction, and the logo temptation
QR codes carry redundancy at four levels, from roughly seven percent recoverable damage up to about thirty. Higher correction means more modules for the same content, so it is a trade rather than a free upgrade.
L · ~7%M · ~15%Q · ~25%H · ~30%The logo in the middle works because the error correction absorbs it. Keep it under about fifteen percent of the area even at level H, and never let it touch the three corner squares. Those are the finder patterns; damage them and the scanner cannot locate the code at all.
Sizes and the quiet zone
The working rule of thumb is that a code should be about a tenth of the intended scanning distance. Two centimetres works when someone can hold it. A poster read from three metres needs roughly thirty. Below about two centimetres, printing tolerances start to matter more than anything in your design file.
The quiet zone is the blank margin around the code, and it is not decorative padding. Scanners use it to find the edges. Four modules of clear space on all sides is the specification; in practice designers crop it to make the code fit, and that single change accounts for a large share of codes that refuse to scan.
Test the printed proof, not the PDF
Every code scans perfectly on a monitor. The failures appear on paper: ink spread closing the gaps between modules, a background image showing through, a fold landing across the middle, the printer's own scaling quietly eating the quiet zone.
Scan the physical proof with two or three different phones, including an old one, at the distance and light people will actually use. Then scan it once more after it has been in a bag for a day. A ten minute check is cheap compared with reprinting a run.
And test what happens after the scan. The destination should be readable on a phone, should not demand a login, and should not itself redirect three more times. A code that scans instantly into a slow page has still failed.