QR Code FAQ
These are the questions we get most often about QR codes in general, as opposed to any one tool on this site. If yours isn't here, the guides go deeper on printing, menus, events and tracking, and you can always email us.
How does a phone read a QR code?
The camera app looks for the three large squares in the corners. They tell the phone where the code is, which way up it sits and how big each module (the small black or white square) is. The phone then reads the grid, corrects any damaged parts using the spare data built into the code, and turns the result back into text. If that text is a web address, the phone offers to open it. Nothing is downloaded and no server is involved in the reading itself; that only happens when you tap the link.
How much can one code hold?
More than you should put in it. The largest QR code can hold a few thousand characters, but every extra character adds modules, and more modules means each one has to be printed smaller for the same size of code. A short web address makes a coarse, easy-to-scan pattern. A whole paragraph of text makes a dense one that fails on a crumpled flyer or across a room. If you have a lot to say, put it on a page and link to that page. The square page builder exists for exactly that.
What does error correction actually do?
A QR code stores extra recovery data so it can still be read when part of it is dirty, scratched or covered. There are four levels: L recovers about 7% of the code, M about 15%, Q about 25% and H about 30%. Higher levels make the code denser, so don't choose H by reflex. M suits most clean print. Q is the safer pick for anything that will be handled, folded or put outdoors, and you need Q or H if you place a logo in the middle, because the logo is effectively damage the code has to recover from.
Why won't my code scan?
Nearly every failure comes down to one of these:
- Too small for the distance. A code needs to be roughly a tenth of the scanning distance wide. The size calculator works it out for you.
- Too little contrast. Dark on light works best. Pale grey, pastel colors and busy photos behind the code all cause trouble.
- No quiet zone. The code needs a clear margin around it, at least four modules wide, with nothing printed in it.
- Too much data. Shorten the link or move the text to a page.
- The link itself is broken. The code may be fine and the page it points to gone. Open the link on its own to check.
Can I print a light code on a dark background?
Some phones will read an inverted code, but many phones and scanner apps won't, and you can't tell which ones your readers carry. If the design really needs it, test on several phones, including an older Android one, before you print a full run. When in doubt, put the code on a light panel inside the dark design.
How should I test a code before printing?
Print one copy at the real size on the real paper, if you can. Scan it with at least two phones, one iPhone and one Android, from the distance people will actually stand at and in the light where it will hang. Check that the page loads quickly on mobile data, not just on your office Wi-Fi. Then print the batch. The print templates give you a starting layout with a safe size and margin.
Can I use the codes for business or sell products that carry them?
Yes. QR codes are free to use under an open standard, and the codes you make here belong to you, with no licence or attribution needed. "QR Code" as a name is a trademark of DENSO WAVE, which only matters if you want to use the words as a brand.
I had a ShareSquare account years ago. Is it still here?
No. An unrelated service used this domain more than a decade ago. None of its accounts, pages or data exist on this site, and old sign-up or invite links now lead to the free generator. If you still have printed codes that pointed to a page on that service, they no longer resolve, and the only fix is a new code. Our codes are static, so a new one won't depend on any account staying alive.