LINKMINT PRACTICAL GUIDE
QR Code Error Correction: Choosing M, Q or H
Choose an error-correction level based on damage risk, data length and final print size instead of automatically selecting the highest setting.
Published and reviewed 5 October 2026 · By the LinkMint Editorial Team · How we test and review
Error correction adds recovery information to a QR code. It can help a scanner reconstruct data when some codewords are damaged, but it does not make poor contrast, a missing quiet zone or a distorted image safe. A higher level also makes the symbol denser for the same content.
The four standard levels
| Level | Approximate codeword restoration | Practical starting point |
|---|---|---|
| L | 7% | Clean, controlled environments where compact size is important |
| M | 15% | A balanced default for ordinary documents and signs |
| Q | 25% | Labels exposed to handling, marks or moderate wear |
| H | 30% | Higher damage risk, after confirming the denser symbol still prints large enough |
DENSO WAVE describes these as approximate restoration rates for total codewords. They are not promises that the same percentage of any visible area may be covered. Damage to finder patterns, severe blur or widespread low contrast can still prevent a scan.
Why the highest level is not always best
For identical content, stronger error correction requires more codewords. The generator may select a larger QR version, which means more modules across the same physical width. If a 25 mm print becomes much denser, each individual module becomes smaller. A scanner may struggle with those tiny modules even though the symbol contains more recovery data.
Shortening the encoded URL or removing unnecessary text can improve the result more than increasing error correction. The goal is a symbol with modules the printer and camera can reproduce clearly.
Choose a level for the environment
- Digital sharing: M is usually a sensible starting point when the image is displayed cleanly.
- Menus and table signs: M or Q can work; test for glare, cleaning and camera distance.
- Warehouse labels: Q may help with scuffs, but label material and print quality matter just as much.
- Outdoor use: start with Q or H, increase physical size and protect the print from fading and abrasion.
Logo overlays deliberately remove or alter modules. Error correction may sometimes compensate, but success depends on placement, size and the encoded data. LinkMint does not add logos because an unmodified symbol is easier to assess and test.
A repeatable comparison test
- Generate the same destination at M, Q and H.
- Print all versions at the intended physical size using the same printer and material.
- Keep the four-module quiet zone intact.
- Scan from the expected distance with at least two different phones.
- Repeat under the dimmest lighting and worst angle expected in use.
- Choose the least dense version that remains reliable in those conditions.
Use the QR Code Generator to compare M, Q and H, then calculate the final dimensions with the QR Print Size Calculator.
Primary sources: DENSO WAVE: Error correction feature and Information capacity and versions.