Why "it scanned on my phone" proves nothing
Reed–Solomon correction has no graceful degradation. Across roughly 5,000 decode attempts, a symbol decoded 100% of the time right up to the last survivable module, and 0% one module later. There is no band where it works sometimes.
That is why the usual quality check fails. Scanning your own code once tells you that you are on the correct side of the cliff. It tells you nothing about how close to the edge you are — and the edge is where a slightly worn print, a cheaper camera or a steeper angle puts you on the other side. The budget meter above exists to show the margin the test cannot.
Static, so nobody can switch it off
Every code here is static: the destination lives in the pattern. Dynamic codes route through a vendor's short URL, which is what makes them editable and also what makes them fragile. One major generator's own help centre states that a deactivated code cannot be revived even by creating a new code with the same content.
For anything you print, that is the whole risk. The sound rule for a vendor is to never withdraw resolution and to charge for mutation instead — some do. We avoid the question by not owning your redirect at all.
Questions people ask
Straight answers. Each one links directly: copy the address after opening it.
How much of a QR code can a logo actually cover?
For a typical URL, about 4% of the area at level L, 9% at M, 14% at Q and 19% at H — measured, not estimated. The widely repeated figure of 30% comes from misreading the standard: ISO/IEC 18004 says level H allows recovery of 30% of the symbol codewords, which is not the same as 30% of the visible area. Three things eat the difference. The finder, timing and alignment patterns carry no error correction at all and are unrecoverable if covered. A solid logo clips codewords partially, and a partial loss counts as a total loss. And correction is applied per interleaved block, not pooled across the symbol.
What contrast does a QR code need?
The governing figure is Symbol Contrast under ISO/IEC 15415, computed as (Rmax − Rmin) / Rmax and graded A to F, where grade C at 40% is the usual acceptance floor. It is not a WCAG ratio. WCAG measures text legibility for human eyes; a camera sensor is a different instrument. Most pages answering this question quote WCAG ratios, which is the wrong unit. What matters in practice is luminance separation, not hue — red on blue decodes reliably while green on red does not, despite both looking equally awkward.
Do rounded or dotted modules stop a QR code scanning?
Rounded modules are effectively free down to about 0.7 of the module diameter. What is not free is styling the three corner finder patterns: measured scan rate drops to 60% and stays there at every error-correction level, because that is a detection failure rather than a correction failure. The scanner uses those patterns to locate the symbol before any error correction runs, so raising the level to H cannot help. If you want a styled code, style the data modules and leave the corners alone.
How far away will my QR code scan?
It depends on module count, not just printed size — which is exactly what the common 10:1 rule ignores. Two codes of the same physical size but different versions have different module sizes and therefore different scan distances. The real threshold is about 2.5 camera pixels per module, below which decoding collapses sharply rather than degrading gradually. Note that phones decode from the camera preview stream rather than a full-resolution still, so a 12-megapixel sensor does not give you 12 megapixels of decoding.
Will this code stop working later?
No. This generator makes static codes: the destination is encoded in the pattern itself, so there is nothing to expire, no account to keep, and no redirect under anyone else’s control. Dynamic QR codes, which most paid generators sell, point at a vendor-owned short URL — convenient because you can change the destination, and a genuine risk because the code dies if that vendor deletes it, changes their terms, or you stop paying. That matters most for anything printed, where you cannot reissue the code.
Is my data sent anywhere?
No. The code is generated in your browser and nothing is uploaded. You can confirm this by opening your network tab, or by disconnecting entirely — the tool keeps working.
Where these numbers come from
Capacity and correction figures are computed from ISO/IEC 18004 for all 40 versions. The logo, style and distance figures were measured locally with a reference encoder and decoder under a camera model — downsampling, blur, sensor noise and JPEG compression. One caveat stated plainly: those decodes used a single decoder implementation, which is more tolerant than a print verifier and possibly more tolerant than the median phone. The budget model is deliberately the conservative side of what we measured.