How do I check a QR code works before I print a thousand flyers?

Why a screen scan is not enough

A screen shows the code large, bright and with perfect contrast. The printed flyer may come out smaller, with lighter ink, on glossy paper that reflects light, and then get folded into a pocket. A thousand copies with one mistake in the link or weak contrast means the whole print bill wasted. Ten minutes of checking costs far less.

The checklist in the tool

1. Content: read the stored-content box in the QR code generator slowly. Is the link complete? Does it start with https? Is there a stray space or character at the end?
2. The link itself: copy the content with the 'Copy the content' button and paste it into your phone's browser. Does the right page open without a login?
3. Contrast: if a warning says the contrast is low or very low, change a color. A good example: navy #1a1a8c on a cream #f5e6c8 background gives 10.84 with no warning.
4. Inversion: red #e60000 on a black background gives a ratio of 4.36, yet the tool warns because the modules are lighter than the background. Do not ignore that warning even when the ratio looks acceptable.
5. Margin: keep the 'Quiet-zone margin' at 4 modules or more, and tell your designer not to put text or images in that frame.
6. File: download SVG for the printer, since it stays sharp at any size, and never hand them a screenshot.

Checking the printed proof

• Ask for a proof on the final paper at the final size, not a print from the office printer.
• Scan it with at least two phones on different systems, and an older phone if you have one.
• Scan from the distance a customer would normally stand, not from five centimetres.
• Try it in the real lighting: warm shop light, or outdoors in the sun if the flyer will be handed out on the street.
• Fold the proof the way it will really be folded, and make sure the crease does not cross the code.

If scanning takes more than a second or two on any phone, fix the cause before printing: make the code bigger, shorten the link, or strengthen the contrast. You can try color shades quickly in the Color contrast checker before bringing them back to the tool.