Why Won't My QR Code Scan?
You printed it, pointed your phone at it, and... nothing. Here's how to diagnose and fix the most common QR code scanning problems.
Quick Checklist
Try these first:
- ☐ Clean your camera lens
- ☐ Move to better lighting
- ☐ Hold steady for 2-3 seconds
- ☐ Try scanning from further back
- ☐ Test with a different phone
1. The QR Code Is Too Small
This is the #1 reason QR codes fail. If the code is smaller than 0.75 inches (2 cm), most phone cameras struggle to resolve the pattern — especially at arm's length.
Fix: Reprint larger. Use the formula: QR size = scanning distance ÷ 10. If people scan from 2 feet away, make it at least 2.4 inches.
2. Not Enough Contrast
QR scanners need a clear difference between the dark modules and light background. Light gray on white, navy on black, or colored QR codes on busy backgrounds often fail.
Fix: Stick to black on white. If you must use color, ensure at least 40% brightness difference between foreground and background.
3. The QR Code Is Damaged or Dirty
Scratches, smudges, fading, or physical damage can break the pattern. QR codes have error correction, but it has limits — especially if key areas (corners, alignment patterns) are affected.
Fix: Clean the surface. If damaged, reprint. Use lamination or protective coating for high-wear environments.
4. Glare or Reflections
Glossy surfaces, glass, and direct lighting create reflections that blind the camera. The scanner sees white glare instead of the QR pattern.
Fix: Change your angle or move to diffused lighting. For future prints, use matte finish materials.
5. Blurry or Low-Resolution Print
If you scaled up a small PNG or printed on a low-quality printer, the module edges blur together. The scanner can't distinguish individual squares.
Fix: Always use vector format (SVG) for printing. Print at 300+ DPI. Regenerate the QR code at the size you need.
6. The URL Is Broken or Invalid
The QR code scans, but the link doesn't work. This isn't a scanning problem — it's a destination problem. The URL might be expired, mistyped, or the site is down.
Fix: Test the URL in a browser. Use a QR code reader app that shows the raw URL before opening. Consider using dynamic QR codes that let you change the destination.
7. Too Much Data Encoded
Long URLs, vCards with lots of fields, or embedded images create dense QR patterns with tiny modules. At small sizes, these become impossible to scan.
Fix: Shorten your URL. Remove unnecessary parameters. If you need to encode lots of data, increase the QR code size proportionally.
8. Colors Are Inverted
Some older scanners expect dark modules on a light background. White QR codes on dark backgrounds may not work on all devices.
Fix: If possible, use traditional dark-on-light orientation. Modern phones handle inversion, but older devices may not.
9. Camera or App Problems
Dirty lens, camera app without QR support, or phone in a case that blocks the camera can all prevent scanning.
Fix: Clean the lens. Try the native camera app (most modern phones have built-in QR scanning). Test with a dedicated QR reader app.
10. Missing Quiet Zone
QR codes need white space (quiet zone) around them — at least 4 modules wide. If text, images, or borders crowd the QR code, scanners can't find the edges.
Fix: Leave clear margin around the QR code. Don't crop it tight or place it against busy backgrounds.
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