1. Minimum Printing Size & Distance
The 2-Centimeter Rule: For standard scanning distances (like on a flyer or packaging), a QR code should never be smaller than 2cm x 2cm (0.8 inches). If printed smaller, many smartphone cameras will struggle to focus on the data matrix.
Distance Formula: A good rule of thumb is a 10:1 ratio. If you want the code to be scanned from 10 meters away (e.g., a billboard), the QR code needs to be at least 1 meter wide. Always test-print your code at the actual size before mass production.