You’ve printed your QR code on a beautiful poster or business card, but your phone won’t read it—and you’re left wondering what went wrong.
QR codes fail to scan for a handful of common reasons. Most have straightforward fixes, and the best part is that you can prevent almost all of them with a little preparation.
In this guide, we’ll walk through the most frequent causes of QR code scanning failures and show you exactly how to fix each one.
TL;DR
QR codes fail to scan most often due to low image quality, poor contrast, incorrect size, missing quiet zone, or damaged surfaces . The solution depends on the cause—use high-resolution images, maintain dark-on-light contrast, ensure codes are large enough for the scanning distance, leave blank space around the code, and always test before printing. If the code appears clean and the device still won’t scan, enable QR scanning in your camera settings or try a dedicated QR scanner app .
Key Takeaways
- Quality matters: A blurry, pixelated, or low-resolution image is the most common cause of scanning failure.
- Contrast is king: QR scanners need to distinguish between dark and light modules. Low contrast means no scan.
- Size and distance: Use the 10:1 rule—1 cm of code for every 10 cm of scanning distance.
- The quiet zone is non-negotiable: Without blank space around the code, scanners can’t detect its boundaries.
- Dynamic codes protect against broken links: If the destination URL changes, a dynamic code can be updated without reprinting.
Common Reasons QR Codes Won’t Scan
Most scanning failures fall into one of these categories:
1. Blurry or Pixelated Image Quality
A blurry QR code is a broken QR code . When the distinct edges of the squares become fuzzy or pixelated, the camera can’t focus . This often happens when you resize a small JPEG or PNG file to fit a large poster .
Fix:
- Use vector formats like SVG or EPS for print—they scale infinitely without losing quality .
- If using raster images, ensure at least 300 DPI at the intended print size .
- Never take a screenshot of a code and expand it .
- Always create a PDF proof at actual print size and test it before ordering .
2. Poor Color Contrast
Smartphone cameras need high contrast between the QR code and its background to distinguish the modules (the dark squares that hold the data) . Black on white works best, but you can use other colors as long as the foreground is significantly darker than the background .
Fix:
- Avoid light codes on light backgrounds (e.g., yellow on white) .
- Avoid dark codes on dark backgrounds (e.g., navy blue on black) .
- Be careful with transparent backgrounds—the changing background can destroy readability .
- If in doubt, use black on white .
3. Missing or Incorrect Quiet Zone
QR codes require a margin of empty space around the border—called the “quiet zone”—to tell the scanner where the code stops and the rest of the design begins . If you crowd the code with text, graphics, or borders, the scanner cannot locate the three corner position markers .
Fix:
- Leave a margin equal to about four modules wide around the entire code .
- Keep the area completely clear of text, images, or borders .
- Use your design tool’s alignment features to maintain proper spacing .
4. Incorrect Size for the Scanning Distance
Size relates directly to scanning distance . A code on a business card can be small because the user holds it in their hand. A code on a billboard must be massive because the user views it from far away .
Fix—use the 10:1 rule:
- Aim for at least 2 x 2 cm (about 1 x 1 inch) for close-up scanning .
- For larger materials, roughly one inch of code for every foot of scanning distance .
- When in doubt, go bigger—nobody complains about a QR code being too easy to scan .
5. Curved, Reflective, or Glossy Surfaces
Surface distortion is a common but often overlooked problem. A QR code on a cylindrical object (like a bottle or mug) becomes distorted, and the camera can’t read the pattern . Reflective or glossy surfaces cause glare, which drops contrast and confuses scanners .
Fix:
- For cylindrical surfaces, position the code flat on the curve and maintain an intermediate scanning distance (typically 30-50 cm) to minimize apparent distortion .
- Avoid placing codes on the most curved part of the object .
- Use matte finishes instead of gloss for printed materials .
- Avoid applying spot gloss directly over the QR code .
6. Damaged or Obscured Codes
Printed QR codes face wear and tear—scratches, tears, fading, or dirt can render them unreadable . Even minimal damage to the pattern can sometimes cause failure .
Fix:
- Laminate printed codes to protect from scratches and weather .
- Place codes in locations where they won’t experience excessive wear .
- When generating the code, choose a higher error correction level (Medium or High) to build in resilience against damage .
7. Broken Links or Expired Content
Sometimes the code scans perfectly but loads an error page. This confirms the QR code image works, but the destination is broken . This typically happens when you delete the linked page, change your website structure, or make a typo during creation .
Fix:
- Use dynamic QR codes—they let you update the destination URL without reprinting .
- Regularly audit campaigns to ensure all links remain active .
- Always test the link before generating the code.
8. Camera or Device Issues
Sometimes the problem is not the QR code but the device trying to read it. Dust on the lens, poor lighting, outdated software, or disabled QR scanning can all cause issues .
Fix:
- Clean the camera lens with a soft cloth .
- Ensure proper lighting—increase screen brightness in low light .
- Enable QR scanning in your camera settings :
iOS: Settings > Camera > Toggle on Scan QR Codes.
Android: Open Camera > Settings > Toggle on Scan QR Codes (or Google Lens suggestions).
- If QR codes still won’t scan, try a dedicated QR code reader app from your official app store .
How Error Correction Affects Scanning
QR codes include error correction that allows them to remain scannable even when partially damaged or obscured. You can choose between four levels when generating a code:
| Level | Recovery Capacity | Best For |
|---|---|---|
| Low | ~7% damage | Digital screens, clean environments |
| Medium | ~15% damage | Business cards, flyers, general use |
| High | ~25% damage | Product packaging, outdoor signage |
| Highest | ~30% damage | Warehouse labels, harsh conditions |
Source: IronQR Documentation , Microsoft Graph API
Key insight: Higher error correction adds redundancy but also increases the pattern density. For most print applications, Medium (~15% recovery) offers a good balance—durable enough for light handling while keeping the code compact . Use High or Highest if you expect wear, scratches, or the code will be printed on a surface prone to damage .
Comparison Table: Common Causes and Fixes
| Issue | Likely Cause | Best Fix | Difficulty |
|---|---|---|---|
| Code looks blurry | Low resolution image | Use vector format (SVG/EPS) or 300 DPI PNG | Easy |
| Code won’t scan at all | Poor contrast or missing quiet zone | Use black on white; add 4-module quiet zone | Easy |
| Code scans but loads error page | Broken URL | Use dynamic QR code to update destination | Moderate |
| Phone scans everything else but not this | Device-specific focus issue | Test on multiple phones; adjust distance | Easy |
| Code on packaging won’t scan | Curved surface distortion | Increase size; scan from 30-50 cm distance | Easy |
| Small code on business card fails | Too small | Minimum 2 x 2 cm (1 x 1 inch) | Easy |
| Damaged code still not scanning | Error correction too low | Regenerate with High or Highest level | Moderate |
Frequently Asked Questions
Why won’t my iPhone scan QR codes?
Check that QR scanning is enabled in Settings > Camera > Scan QR Codes. If it’s on and still not working, clean the lens, adjust the distance, or try a QR reader app .
Can a QR code be too big to scan?
Yes. If the code is too large and the camera can’t capture the full pattern in frame, it won’t scan. The 10:1 rule works both ways—ensure the scanning distance is appropriate for the code size.
What’s the best color combination for a QR code?
Black on white is the most reliable. If you must use brand colors, ensure strong contrast—dark foreground on a light background. Avoid light-on-dark or low-contrast combinations .
Can I fix a QR code that doesn’t scan after printing?
If the issue is a broken link, use a dynamic QR code generator to update the destination without reprinting. If the issue is image quality, contrast, or size, you’ll need to regenerate and reprint .
What’s the minimum size for a scannable QR code?
At least 2 x 2 cm (about 1 x 1 inch) for close-up scanning. For larger materials, scale up with the 10:1 rule—1 cm per 10 cm of scanning distance .
Putting It All Together
A QR code that won’t scan is frustrating, but the fix is usually straightforward. Start with the basics: check image resolution, ensure high contrast, confirm the quiet zone, and test the destination URL.
For future campaigns, prevent problems with a simple checklist:
- Use vector or high-res images (300 DPI for print)
- Maintain strong contrast (dark on light)
- Leave a 4-module quiet zone
- Size appropriately with the 10:1 rule
- Choose Medium or High error correction
- Test on multiple devices before printing
- Use dynamic QR codes to future-proof against broken links
When in doubt, print a sample and test it in real-world lighting conditions. A few minutes of testing can save you from thousands of reprints.
Still having trouble? Walk through the checklist above—one of these fixes should get your QR code scanning again. Drop any questions in the comments—we’re here to help.
Sources
- Be Connected – How to Scan QR Codes
- QR Code Generator – QR Code Scanning Problems and Solutions
- VistaPrint – How to Fix a QR Code That Won’t Scan
- Scanova – Fix QR Code Issues: How to Solve QR Code Scanning Errors
- Iron Software – QR Code Error Correction Levels
- Dynamsoft – Why QR Code Scanning Fails in Real-World Conditions
- EurekAlert! – Methodology to Read QR Codes on Uneven Surfaces
- Microsoft Graph API – QR Code Error Correction Levels
