Few things are more frustrating than a QR code that will not scan, especially if it is already printed on a thousand flyers. The good news is that most failures come from a short list of causes, and many can be fixed or worked around. Use this checklist to diagnose the problem, whether you are the person scanning or the person who made the code.
If you are trying to scan a code
Start with the phone, because it is the quickest thing to check.
1. Use the built-in camera app
Most modern iPhones and Android phones can read QR codes directly from the camera app. Point the camera at the code, hold steady, and wait for a notification or link to appear. If nothing happens, check that QR scanning is enabled in your camera settings; some Android devices also offer scanning through Google Lens.
2. Clean the lens and hold steady
A smudged lens is a surprisingly common culprit. Wipe it, then hold the phone steady and square to the code, not at a steep angle.
3. Move closer, or farther
If the code fills too little of the frame, the camera may not resolve the details. If it is too close, the camera may not focus. Try moving slowly toward and away from it until it reads.
4. Fix the lighting
Dim light, harsh shadows and glare all interfere. Step out of your own shadow, tilt the phone to avoid reflections on glossy surfaces, or turn on the flashlight in dark places.
5. Try a screenshot
If the code is on a screen or in an image you received, you can often scan it from a screenshot using your phone's photo app or Google Lens.
If you made the code
If the code fails on several phones in good conditions, the problem is probably the code itself.
6. It is too small for the distance
This is the most common design problem. A frequently used rule of thumb is to make the code about one tenth of the scanning distance in width. A poster read from a couple of meters away needs a much bigger code than a business card. See QR code size for print for practical sizes.
7. It contains too much data
Long URLs, full contact details or large blocks of text create dense codes with tiny modules. Shorten the link, remove optional fields, or point the code at a simple web page instead.
8. The quiet zone is missing
The QR standard calls for a blank margin four modules wide around the code. If text, borders or background images crowd the edges, scanners may fail to detect the code. Add a plain light margin around it.
9. Contrast is too low or colors are inverted
Light modules on a light background, pastel colors, or busy backgrounds make codes hard to read. Dark modules on a light background are the most reliable. Inverted codes (light on dark) are not supported by all scanners, so avoid them for anything important.
10. The print is blurry or distorted
Enlarging a small PNG, heavy JPG compression, low-quality printing, or printing on textured or curved surfaces can blur or warp the modules. Export as SVG or a high-resolution PNG, print a proof at actual size, and test on the final material.
11. A logo or design covers too much
QR codes include error correction, so a small logo can work, especially at a higher correction level. But a large logo, or one that covers the three corner "finder" squares, will break the code. Keep logos small and central, and leave the corners untouched.
12. The code works, but the link does not
Sometimes the code scans perfectly and the problem is the destination: a typo in the URL, a deleted page, an expired campaign link, or a site that does not load well on mobile. Scan the code yourself and follow the link to the end. If you used a third-party "dynamic" QR service, check whether the subscription or redirect is still active, because the code depends on that service.
WiFi and contact QR codes
These codes have their own common problems:
- WiFi codes: the network name and password must match exactly, including capital letters, and the security type (such as WPA/WPA2 or none) must be correct. Some special characters need to be escaped in the WiFi format. Our WiFi QR guide covers the details.
- vCard codes: too many fields make the code dense, and some phones handle certain fields differently. Keep it to the essentials. See the vCard QR guide.
Static vs dynamic codes
A static QR code stores the content directly, such as the URL itself. It does not expire and does not depend on any service; if the destination page is still online, the code keeps working.
A dynamic code stores a short redirect link from a service, which then forwards to your destination. It can be edited later and may offer analytics, but if the service shuts down or the account lapses, the code stops working.
The QR Studio generator creates static codes in your browser, which avoids that dependency.
A quick pre-print checklist
- Content is as short as possible (short URL, minimal fields).
- Size suits the scanning distance.
- Quiet zone is clear on all four sides.
- Dark modules on a light, plain background.
- Exported as SVG or high-resolution PNG.
- Logo, if any, is small and corners are untouched.
- Printed proof scans on at least two phones in real lighting.
- Destination link works on mobile.
- A short call to action explains what scanning does.
For a full walkthrough, read how to make a QR code and the QR code size guide.
A note on safety
Be cautious about scanning codes in public places, such as stickers on parking meters, that might have been placed over a legitimate code. After scanning, check that the link preview shows the domain you expect before opening it, and do not enter payment details or passwords on unfamiliar sites.
Frequently asked questions
Why is my QR code not scanning?
Common causes are a code that is too small, too much data, a missing quiet zone, low contrast, blurry printing, or a broken destination link. Test on multiple phones to narrow it down.
Can I fix a QR code that is already printed?
If the code itself is unreadable, you will usually need to reprint it. If the issue is the destination, fixing the web page or redirect can solve it without reprinting.
Do QR codes expire?
Static QR codes do not expire. Dynamic codes can stop working if the service or subscription behind the redirect ends.
Why does my QR code scan on one phone but not another?
Camera quality, software and settings differ. Codes that are small, dense, low-contrast or inverted are more likely to fail on some devices.
Is it safe to scan any QR code?
Not always. Check the link preview before opening it, and be wary of codes in public places that may have been tampered with.
Keep reading