QR Code
QR Code has become a commodity. Any app generates one in seconds — and that's exactly why most QR Codes on packaging don't work the way they should.
The problem isn't generating the code. It's understanding what happens after it leaves the file and lands on a printed substrate.
Minimum size. A QR Code that is too small will not read on a smartphone camera in poor ambient light, packaging with glare, or at an oblique angle. The recommended minimum for printed packaging is 2cm by 2cm under ideal conditions. For physical retail, with artificial lighting and a moving consumer, work with at least 3cm by 3cm.
Contrast. The reader needs to distinguish dark modules from a light background. A colorful QR Code, one placed on a patterned background, or one placed on a warm color increases error rates. When the design requires color, the test must be done on the final substrate, not on screen.
Quiet zone. The QR Code needs a white space border equivalent to four modules on each side. Pushing the code to the edge of the packaging or next to text is the most common error in projects without technical review.
Error correction levels. The standard has four levels: L, M, Q and H. Level H allows reading even with up to 30% damage or dirt. For consumer packaging, consider Q or H depending on the product's destination.
The link destination matters as much as the code itself. A QR Code that leads to a slow page or one that doesn't render well on mobile wastes all the work that came before it.