QR code not scanning? Check these 9 things

If a QR code won't scan, the file or print is usually the cause. Check these things in order; the first checks take seconds.

How to scan.

1. Scan the file on a screen

Scan the original file on a computer screen with your phone. If it fails there too, the problem is the file or link, not the printer. Make the code again before continuing.

2. Try two different phones

Scan the print with two phones, one of them a few years old. If one reads it and the other doesn't, the code is borderline. It probably needs to be bigger, clearer or higher in contrast.

3. Is it big enough for the distance?

The farther away people stand, the bigger the code must be. A good rule is that the code should be at least one tenth of the scan distance, and never smaller than 0.8 in (2 cm). Each dot in the pattern should be at least 0.7 mm wide. A code that holds a lot, like a contact card with every field filled in, needs more room (tips for business cards). Our guide to printing QR codes has a table by distance.

4. Is the white border still there?

Every code needs a clear border, 4 dots wide, on every side (printers call it the quiet zone). Scanners use it to find the code. Check that no text, line, photo or page edge runs into it, and that nobody trimmed it off.

5. Is the contrast strong enough?

Phones read dark codes on a light background best. Aim for a contrast of at least 4.5 to 1, and black on white is safest. Light dots on a dark background are risky, because some scanner apps can't read them at all. Pale colors on pale paper fail too.

6. Glare, gloss and curves

A glossy finish, a laminate or a sheet of glass can flash light straight back at the camera. Matte paper is safer. A code on a bottle or a can bends with the surface, so keep it small compared with the curve, and test it on the real object.

7. Is the printed code the one you made?

Sometimes a designer or printer rebuilds a code, or an old version slips into the layout. Scan the printer's proof, not just your own file, and check that it opens your link.

8. Does the page open?

If the code scans but nothing loads, check the link. It might have a typo, the page might have moved, or the file might be too large to load on a phone. Open it on a phone using mobile data, not your office Wi-Fi.

9. Is the service behind it still on?

If the code opens an upgrade, "expired" or "paused" page, it's an editable code whose plan has ended. Why QR codes stop working, and how to fix it.

Fix it without reprinting

If the code is editable and the link is the problem, sign in and change the link. Saving the new destination updates the link behind every printed copy. Saved pauses and access restrictions still apply. If the print itself is the problem, you'll need a new print. A sticker at least as big as the old code, covering it completely, is often cheaper than a full run.

What the free maker checks for you

Our free QR code maker has a checker beside the preview:

It checks contrast, the white border and the size for your scan distance.
It won't let you download a code whose dots are too small or whose colors are too faint to scan.
The SVG, PDF and EPS files keep the width you entered, so they print at the right size. Which file to use.

Then print one copy at full size and scan it with two or three phones, in bright light and in shade, from where people will really stand.