miji.beThe minimum QR code size refers to the smallest printed dimension at which a smartphone camera or dedicated scanner can reliably read the code. If the code is too small, scanning fails and the user experience suffers.
As a general guideline, when scanning from 10-20 cm with a smartphone, the QR code should be at least 2 cm (20 mm) per side. However, this assumes a low-version QR code with minimal data. As data volume increases, the number of modules (cells) grows and each cell becomes smaller, requiring a larger overall code for the same scanning distance.
Shortened URLs have a significant impact on QR code size. A 100-character original URL versus a 25-character shortened URL results in different QR code versions (module counts). Shorter URLs produce lower-version codes with larger cells, making them easier to scan at smaller sizes. This is especially valuable on business cards and flyers where print space is limited.
A practical formula for determining minimum size is: minimum size = scanning distance / 10. For a 30 cm distance, aim for 3 cm; for 1 m, aim for 10 cm. For posters and signage read from greater distances, scale up accordingly.
Print quality also matters. High-resolution laser printers render small cells crisply, but inkjet printers or offset printing may cause ink bleed that obscures cells. Always do a test print and verify scanning with an actual smartphone before committing to a final size.