Error correction adds redundant data so a damaged code still reads. Higher levels survive more damage but make a physically larger code for the same content.
- H (30%) — use this for anything engraved, etched, or on a curved surface. Fill inconsistency and material grain both eat modules.
- Q (25%) — print on textured or curved surfaces.
- M (15%) — flat paper print. Usually plenty, and noticeably smaller.
- L (7%) — screens only.
The tool defaults to H because that is the right default for makers. If you add a logo or badge to the centre, it forces H automatically, since the image covers modules that error correction then has to rebuild.
Aug 28, 2026