QR Code Error Correction Levels Explained (L, M, Q, H)
One of the key features of QR codes (Quick Response codes) is their ability to withstand damage and dirt while remaining fully scannable. This is handled by Reed-Solomon error correction.
The Four Error Correction Levels
There are four distinct error correction levels, each offering a trade-off between scannability safety and data density capacity:
- Level L (Low): Recovers up to 7% of lost or damaged data. Offers the lowest density grid (cleanest look) but has minimal resistance to damage.
- Level M (Medium): Recovers up to 15% of data. Standard default for general links.
- Level Q (Quartile): Recovers up to 25% of data. Good for industrial or harsh environment prints.
- Level H (High): Recovers up to 30% of data. Necessary when overlaying center brand logos.
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Why Level H is Required for Branding Logos
When you place a logo in the center of a QR code, the scanner sees the logo as a damaged/blocked area of the grid. By generating the QR code using Level H (30% recovery), we ensure that the surrounding modules contain enough redundant mathematical data to fully reconstruct the link payload during scanning.