Two-dimensional Reed-Solomon coding
QR (Quick Response) codes were created by Denso Wave in 1994 and are now standardized as ISO/IEC 18004. Data is laid out on a matrix and protected by Reed-Solomon error correction, so the code remains readable even when partially damaged. Four correction levels are available: L (~7%), M (~15%, default), Q (~25%), H (~30%). Higher levels are more robust but can store less data.
Static vs. dynamic QR: this tool generates static QR codes — the content is baked in and cannot be changed later. Dynamic QR codes redirect through a short link whose target you can edit after printing; useful for campaign tracking. Static is fine for business cards and permanent menus.
About QR codes
Version 40 (largest) with level L supports ~2,953 binary bytes, 4,296 alphanumeric characters, or 7,089 pure digits. But as data grows, modules shrink and scanning becomes harder; in practice URLs of 100-300 characters are the sweet spot.
Use H if you plan to overlay a logo, if the surface may get scratched or dirty, or if it will be scanned in low light — the code remains readable with up to 30% damage. M is fine for clean, controlled surfaces.
Yes. Keep the foreground dark and background light (at least ~40% luminance difference). If you embed a logo, use level H and keep the logo below 15-20% of the code area. Always test with multiple scanners — iPhone and Android cameras have different tolerances.
Rule of thumb: print size = scan distance / 10. Example: a poster scanned from 2 m away needs at least a 20 cm QR. Aim for minimum 2 dots per module in print (at 300 DPI that is ~0.17 mm per module). Vector (SVG) output always prints sharper than raster.
Digital ad campaigns
QR codes, outdoor ads, social media and Google Ads — grow with KEYDAL performance marketing.