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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →No single percentage tells you whether a damaged QR code will scan. The often-cited 15% figure for Level M error correction refers to approximate recovery of total codewords—not permission to cover 15% of the visible square. The claimed 0.7% failure threshold is not established as a general rule by the official sources cited here.
What the 15% QR code figure actually measures
DENSO WAVE describes QR Code error-correction rates as a proportion of the symbol’s total codewords. A codeword is eight bits, so the percentage concerns encoded data units—not the percentage of pixels, modules, or visible square that may be covered. The figure is approximate and depends on the error-correction level used when the code is created. DENSO WAVE’s error-correction explanation gives the mechanism and qualification.
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For Level M, DENSO WAVE lists an approximate recovery rate of 15% of total codewords. That does not mean a sticker can safely cover 15% of every QR code. Whether a particular symbol remains readable also depends on where and how it is damaged.
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QR Codes use Reed–Solomon error correction: redundant information is added to the encoded data so a decoder can recover some data when parts are dirty or damaged. DENSO WAVE explains that correction works at the byte level and is useful for concentrated burst errors. It does not make a code immune to damage; recovery depends on the available correction capacity and the damage.
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Approximate recovery rates by level
| Level | Approximate share of total codewords recoverable |
|---|---|
| L | 7% |
| M | 15% |
| Q | 25% |
| H | 30% |
These are approximate codeword-based rates published by DENSO WAVE’s QR Code standardization page; they are not guarantees about covered surface area. The appropriate level depends on operating conditions and code size. A higher level offers more correction capacity, but the table alone cannot predict whether a specific damaged image will scan.
Why a small mark can matter more than a larger one
Damage percentage leaves out the location and shape of the mark. A decoder must first locate and interpret the QR symbol; an obstruction affecting those functions can disrupt reading even if it covers little area. Other damage may be recoverable if it affects data that the code’s error correction can restore. The cited sources do not provide a formula that converts damage area or location into a pass-or-fail prediction.
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DENSO WAVE warns that an overlay or design can deform a code and that a tiny missing or smeared part may make reading impossible or slow it. That is a caution about how damage can affect reading, not a finding that every tiny mark causes failure. Its FAQ does not establish a 0.7% cutoff.
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Is a sticker covering 15% safe, or does a 0.7% erasure kill the code?
Neither statement is a universal QR Code rule. DENSO WAVE’s approximate 15% figure applies to total codewords at Level M, not to visible area covered by a sticker. The official sources cited here do not establish that erasing 0.7% of a code reliably makes it unreadable. Without a named code and defined test conditions, those two area figures cannot be compared as general scan thresholds.
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- 【Ergonomic Design】 The curved handle is extended and thickened, tailor-made for North America customers. Specially designed smooth and flat trigger for better grip. 【Package Includes】Barcode Scanner x1, USB Cable x1, Dongle x1, User Manual x1
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- 【Digital and Printed 1D 2D QR Bar Code Symbologies】1D: Codabar, Code 11, Code93, MSI, Code 128, UCC/EAN-128, Code 39, EAN-8, EAN-13, UPC-A, ISBN, Industrial 25, Interleaved 25, Standard25, Matrix 2D: QR, DataMatrix, PDF417, Aztec, Hanxin, Micro PDF417. (Note: Not compatible with Square.)
A meaningful test would need to identify the code’s error-correction level, the amount and type of encoded data affected, whether the damage overlaps structure needed to locate or interpret the symbol, and the printing and scanning conditions. The available official references describe the correction levels and warn that damage can prevent reading, but do not quantify results across those variables.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What to do if a QR code is damaged
- For a code you need to scan: try a clean, unobstructed copy rather than relying on an area-percentage rule.
- For a code you are creating: choose an error-correction level suited to its expected conditions and test the finished, printed code with the scanners and viewing conditions people will actually use. DENSO WAVE advises choosing a level with operating conditions and QR Code size in mind.
- For a claim about a precise cutoff: ask for the specific code, correction level, damage pattern, and reproducible scan setup. A percentage without those details does not establish a reliable limit.
For an overview of QR Code structure, see DENSO WAVE’s explanation of what a QR Code is.
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