Data capacity

How much a QR code can store depends on the version (grid size), the error-correction level (redundancy eats capacity), and the encoding mode. Numeric packs tightest, then alphanumeric, then raw bytes for arbitrary URLs and text. A bigger payload forces a higher version, which means denser modules.

For printed codes you almost never want to fill the capacity, because density hurts scannability. Encoding a short redirect URL instead of a long campaign link keeps the code sparse and reliable. See the version capacity table for the exact limits.