Error correction allows a QR code to be scanned even if part of it is damaged or obscured. QR codes use Reed-Solomon error correction with four levels: L (7%), M (15%), Q (25%), and H (30%).
Reed-Solomon codes add redundant data modules to the QR pattern. If some modules are unreadable (due to dirt, scratches, or a logo overlay), the decoder can reconstruct the missing data. Higher levels mean more redundancy but also a denser (larger) QR code.
Use level H to safely place a logo in the center of your QR code.
Use level Q or H for codes exposed to weather and wear.
Level L is sufficient for clean digital displays.
Use M for most cases. Use H if you're adding a logo. Use L only for very long URLs where size matters.
Yes. More redundancy means more modules, resulting in a denser pattern that needs to be printed larger.
No. Changing the level regenerates an entirely different QR code pattern.
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