The 10:1 Scanning Ratio Rule
As a general optical standard, the physical size of a printed QR code should be approximately 1/10th of the distance from which the user will scan it.
- Business Cards (25 cm distance) -> Minimum 2.5 cm × 2.5 cm
- Restaurant Table Menus (45 cm distance) -> Minimum 4.5 cm × 4.5 cm
- Posters & Window Signs (1.5 m distance) -> Minimum 15 cm × 15 cm
- Trade Show Banners (3 m distance) -> Minimum 30 cm × 30 cm