Error correction, made visible

QR Code Error Correction Levels: Compare L / M / Q / H

The same content at all four levels side by side. Drag the slider to simulate damage and a real decoder tells you live which levels still scan.

The QRDIV error correction comparator renders the same content as four QR codes at levels L, M, Q and H, lets you drag an occlusion slider to simulate stickers or dirt, and runs a real decoder on each damaged code to report whether it still scans - size and version differences included, entirely in your browser.

01

Four levels · real damage test

Change the content to see size differences; drag the slider to test resilience - verdicts come from a real decoder, not theory

Content
Center occlusion area · 0%Simulates a sticker or stain over the middle; verdicts come from a real decode attempt
Lrecovers up to 7%
Mrecovers up to 15%
Qrecovers up to 25%
Hrecovers up to 30%
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How to choose a level

Higher correction survives more damage but makes the code denser for the same content. The decision comes down to how dirty the environment gets and whether you add a logo.

LevelCorrection capacityBest for
Lrecovers up to 7%On-screen display, short links, sparsest and easiest to scan
Mrecovers up to 15%General default for ordinary printed material
Qrecovers up to 25%Codes with logos, table cards and other dirt-prone spots (site default)
Hrecovers up to 30%Industrial labels and outdoor placements with heavy wear
Real-world tolerance is usually below the theoretical figure: the percentage covers recoverable data codewords, so damage concentrated in one spot - or covering a corner finder pattern - can defeat any level. That is exactly why this page uses a real decoder for its verdicts.
Adding a logo? Use Q or H - a logo is deliberate occlusion and eats into the recovery margin of lower levels.
FAQ

Frequently asked questions

No. Higher levels make the code denser: the same content at H needs several versions more modules than at L, which scans worse when printed small. Use L or M in clean settings; reserve Q or H for dirt, wear or logos.