Error Correction Level

Error correction level indicates the strength of a QR code's ability to restore data correctly even when partially dirty or damaged. Implemented using Reed-Solomon codes, four levels are available: L (~7% recovery), M (~15%), Q (~25%), and H (~30%).

Higher levels increase durability but add redundant data, making the QR code larger for the same data volume. Level M is recommended for general use, while H is chosen when overlaying a logo in the center.