QR codes have evolved from a niche automotive industry tool to a ubiquitous part of daily life. From restaurant menus to payment systems, contact sharing to product authentication, QR codes bridge the physical and digital worlds.
How QR Codes Work
A QR (Quick Response) code is a two-dimensional barcode that encodes data in a matrix of black and white squares called "modules." Three large squares in the corners (finder patterns) help scanners orient the code. Smaller alignment patterns and timing patterns provide additional orientation data.
Error Correction Levels
QR codes include redundant data for error correction, allowing them to be read even when partially damaged:
- Level L (Low): ~7% can be damaged
- Level M (Medium): ~15% can be damaged (default)
- Level Q (Quartile): ~25% can be damaged
- Level H (High): ~30% can be damaged
Use Level H when adding a logo overlay (the logo obscures some data, so higher error correction compensates). Use Level L for maximum data capacity when the code will be displayed on screens.
Best Practices for Print
Minimum size: 2x2 cm (0.8x0.8 inches) for close-range scanning. Scale up proportionally for distance: 10 cm for 1-meter viewing, 30 cm for 3-meter viewing.
Quiet zone: Maintain white space equal to 4 modules around the QR code. Without this margin, scanners may fail to detect the code boundaries.
Contrast: Use dark modules on a light background. The foreground-to-background contrast ratio should be at least 4:1. Avoid placing QR codes on patterned or photographic backgrounds.
Common Mistakes
Encoding too much data: More data means a denser, harder-to-scan code. Keep URLs short (use URL shorteners if needed). Inverting colors: Light-on-dark QR codes work but scan less reliably. Low-resolution printing: QR codes must be crisp — blurry modules cause scan failures.
Create custom QR codes with our QR Code Generator or decode existing codes with our QR Code Scanner.