QR code error correction explained (L, M, Q, H) and printing tips

Error correction is how much of a QR code can be dirty, damaged or covered and still scan. QR code generator lets you choose.

The four levels

• Low (L): about 7% repairable, simplest code.
• Medium (M): about 15%, the recommended default.
• Quartile (Q): about 25%, more repair.
• High (H): about 30%, best for print or when a logo covers the centre.

Higher levels need more squares, so the code becomes denser. Dense codes must be printed larger to scan.

Choosing

• On-screen link: Medium.
• Printed poster, sticker or card: High.
• Very long text: Low, otherwise it may not fit. The tool shows a message if the text is too long.

Size and format

• Size is in pixels. 512 is fine for screens; use 1024 or more for print.
• SVG never blurs, however big you print it, so prefer it for print jobs.
• Quiet border is the empty margin around the code. Keep 2-4 squares.

Colours

Keep the foreground dark and the background much lighter. Inverted codes (light on dark) and low contrast often fail. You can check ratios with Color converter.

Before you print

Scan the code with two different phones at the final size. Make sure the link works on mobile, and keep it short, since shorter links make simpler codes.