QR Code Not Scanning? Nine Causes and the Fix for Each

Remake the code freeDownload the QR code pre-print test checklist (PDF)

First, which kind of failure is it?

There are two different failures that both get called "not scanning". In the first, the phone camera does not react at all: no link, no prompt. That is a problem with the printed code or the camera. In the second, the phone reads the code but what opens is wrong: a page not found, a Wi-Fi network that will not join, a contact with missing details. That is a problem with what the code contains.

Work out which one you have before changing anything. If even one phone reads the code, the pattern is fine and you can go straight to the last section.

Nine causes, in the order to check them

1. Low contrast or inverted colours

Phone cameras look for dark modules on a light background. Pale codes, mid-grey on white, and especially light codes on dark backgrounds fail often. The free QR code generator warns you when the two colours are too close or when the code is lighter than its background. Fix: a dark code colour on white or a very light background.

2. No white border

The quiet zone is the clear margin around the code that tells the camera where it starts. Denso Wave's guidance says a QR code requires a four-module wide margin on all sides. Designers often crop it to fit a layout, or place the code against a busy photo. Fix: use the Standard border in the generator and keep it when you place the image.

3. Printed too small

Each module has to be large enough for the camera to separate it from its neighbours. Divide the printed width by the number of modules plus 8; if the answer is under about 0.5 mm, make it bigger. Our QR code size guide has a chart.

4. Too much in one code

Long links with tracking, or a contact card with every field filled in, create dense codes with tiny modules. Fix: shorten the link, trim the contact card to what people need, or point the code at a short page that holds the details.

5. A logo that is too big, or the wrong error correction

A logo covers modules, and the code relies on error correction to rebuild what is hidden. Denso Wave describes the levels as restoring roughly 7, 15, 25 and 30 percent of the data, and notes that M (15%) is the level most often selected. When you add a logo, the generator switches to H automatically, keeps the logo between 12 and 22 percent of the width, and clears the modules beneath it. If you put a logo on a code in another tool, check that it uses H, and keep the logo near the 18 percent default.

6. Stretched or skewed

Dragging a corner in a document editor can squash the code in one direction. QR codes must stay square. Fix: resize with the aspect ratio locked, or use the SVG.

7. The surface: gloss, curves, folds

Glossy lamination throws back light, a code on a bottle bends away from the camera, and a fold across a flyer breaks the pattern. Fix: matt finish, a flat area, and keep the code away from folds and edges.

8. Light and distance

A code that scans at a desk can fail in a dim restaurant or behind a sunny window. Apple's iPhone guide suggests tapping the flashlight to add light when scanning with the Code Scanner. Fix the cause where you can: move the sign, or make the code bigger for the distance.

9. The destination has changed

This is the "reads but fails" case. The page was moved, the domain lapsed, the Wi-Fi password changed, or a phone number is out of date. Open the link on a phone over mobile data, not just your office Wi-Fi, and check every detail in the code.

When the phone is the problem

If one phone fails and others succeed, the code is fine. Clean the lens, hold the phone steady with the whole code in the frame, and move back a little; phones cannot focus very close. On an iPhone, try both the Camera app and the Code Scanner in Control Center, which Apple's guide shows how to add. Most Android phones read codes from the camera app or from Google Lens.

It is worth knowing which phone your customers carry, but you cannot test them all. Test on at least one iPhone and one Android phone, preferably one of them a few years old, and you will catch nearly every printing problem.

Fix it once, then prevent it

Most scanning failures come from a code that was fine on screen and changed in printing: cropped, shrunk, laminated. Run the checklist in this post's PDF on a single printed copy before any print run, and keep the SVG of the final code so the next reprint does not start from a screenshot.

If a destination is likely to change, a static code will keep failing every time it does. Point it at a page on your own site that you can update, or use a dynamic code; our static vs dynamic guide explains the trade-off, and Fynl's paid plans include dynamic codes you can re-point and that count scans. For Wi-Fi codes that read but do not join, see the Wi-Fi QR code guide.

The QR code generator is one of several no-sign-up tools on our free tools page, including a UTM builder for tagging the links you put in codes and a Google review link generator.

Questions people also ask

Sources

• DENSO WAVE — Points for generating QR Code (quiet zone)
• DENSO WAVE — Error correction feature
• Apple iPhone User Guide — Scan a QR code with your iPhone camera