How QR code error correction works
Ever noticed a QR code still scans with a logo in the middle or a scratch across it? That's error correction — built-in redundancy that lets a scanner rebuild missing data.
The four levels
- Level L (Low) — recovers about 7% of the code.
- Level M (Medium) — about 15%.
- Level Q (Quartile) — about 25%.
- Level H (High) — about 30%.
The trade-off
Higher error correction survives more damage but adds more modules, making the code denser for the same amount of data. For clean digital use, a lower level keeps the code simple; for printed codes that may get scuffed — or codes with a logo overlaid — a higher level is safer.
FAQ
- How much of a QR code can be damaged and still work?
- Up to roughly 30% if it was generated at the highest error-correction level (H). At lower levels the tolerance is smaller. Either way, a clean, undamaged code always scans most reliably.
Scan and create QR codes in a tap
Scan QR Code Master is an ad-free QR and barcode scanner and generator, free to download for iPhone, iPad, and Mac — with history and one-tap sharing.
Download on the App StoreRelated guides
- What is a QR code and how does it work?
- QR code not scanning? How to fix it
- How to share and print a QR code
- Static vs dynamic QR codes: what's the difference?
- Are QR codes safe? How to scan safely
- How big should a QR code be?
- How to change the color of a QR code (and keep it scannable)
- QR code vs barcode: what's the difference?
- How to add a QR code to your resume
- How to test a QR code before printing it