Core Concepts
QR Code Module
A module is the smallest single black or white square in a QR code — the individual building block that the whole scannable pattern is made of, comparable to a pixel in an image.
Every QR code is a grid of modules, and the grid size depends on the code's "version" (see the Version entry) — anywhere from 21×21 modules at the smallest to 177×177 at the largest. More data means more modules, which means a denser, more detailed pattern.
Module size matters most when printing: shrink a QR code too far and individual modules blur together or drop below what a camera can resolve at typical scanning distance, which is the most common cause of a code that looks fine on screen but fails to scan once printed small.
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