QR Code Error Correction: Why Damaged Codes Still Scan
Error correction is the safety net built into every QR code, letting it recover data even when part of the pattern is missing.
Every QR code reserves some of its space for backup data, so it can still be read if a portion is scratched, smudged or covered by a logo. This is called error correction, and it comes in four levels that trade capacity for resilience. Knowing how the levels differ helps you decide when to play it safe and when to keep the code small and simple.
QR codes carry Reed-Solomon error correction, so at the highest level about 30% of the pattern can be damaged and still scan.
Why it works
Four levels to choose from
Levels L, M, Q and H recover roughly 7%, 15%, 25% and 30% of the data if part of the code is lost.
Higher recovery, denser code
More protection means more modules packed in, so a high level makes the pattern look busier.
Logos need higher levels
Placing a logo over the centre covers data, so a higher level keeps the code readable.
Match the level to the risk
Use more correction for print and outdoor use, and less when the code is clean and on screen.
How to create yours
- 1
Estimate the risk of damage
Think about whether the code will be printed, handled, placed outdoors or kept safely on a screen.
- 2
Pick a starting level
Choose M for everyday use, and step up to Q or H when damage or a logo is likely.
- 3
Add any logo or styling
If you place a logo, raise the level so the covered area stays within what can be recovered.
- 4
Test under real conditions
Scan the code in the setting it will live in to confirm the chosen level holds up.
Ideas & examples
Code with a centre logo
Level H lets a brand mark sit in the middle without breaking the scan.
Outdoor or printed code
A higher level survives scuffs, weather and small print imperfections.
Clean on-screen code
Level L or M keeps the pattern simple when there is little chance of damage.
Common questions
Which error correction level should I pick?
Level M suits clean flat prints. Choose H when a logo overlays the centre or the surface takes daily wear.
Does higher error correction slow scanning down?
A touch, since density increases. On a cleanly printed code you will never notice the difference.
Ready to create yours?
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