Reference
QR code reference tables
The numbers you actually need: error-correction recovery, data capacity by version, print size by scanning distance, supported data types, and redirect codes.
QR code error correction levels
QR codes carry redundant data so they still scan when smudged, scratched, or partly covered by a logo. The error-corr...
QR code version capacity
A QR code's "version" is its grid size, from version 1 (21×21 modules) to version 40 (177×177). Bigger versions hold ...
Scan distance to minimum print size
The rule of thumb for QR codes is a 10:1 ratio: the printed code should be at least one-tenth as wide as the farthest...
Supported QR code data types
A QR code can carry more than a URL. The phone's camera decodes the payload and decides what to do with it: open a li...
HTTP redirect status codes
When a server wants to send a browser to a different URL, it answers with a redirect status code. The differences bet...
QR code glossary
The terms behind the numbers, each defined in one plain sentence.
QR code answers
Direct fixes for the most common QR code problems.