A QR code that doesn't scan is worse than no QR code at all — it wastes print space and frustrates the customer trying to use it. These five mistakes cause the vast majority of scanning failures.
1. Too little contrast
Light-colored codes on light backgrounds (or the reverse — dark on dark) are the number one cause of scan failures. Keep the code dark on a light, plain background whenever possible, and test any custom color combination before committing to print.
2. A logo that's too big
A center logo covering more than roughly 15-20% of the code's area can destroy enough of the underlying data pattern that phones can't decode it, especially on codes with less built-in error correction.
3. Printing too small
A QR code shrunk to fit a tight design space may look fine to the eye but fail to scan — as a rule of thumb, print at least 2cm x 2cm for close-range scanning (business cards, receipts) and larger for anything scanned from further away (posters, banners).
4. No quiet zone around the edges
QR codes need a small margin of blank space around them to scan reliably. Placing a code flush against text, images, or the edge of a page confuses most scanner apps.
5. Not testing before mass-printing
Always scan the final printed version — not just the on-screen preview — with two or three different phones before ordering hundreds of copies. Ink absorption, paper texture, and lamination can all subtly affect scannability in ways a screen preview won't show.