The Scanning Distance Formula
A reliable rule of thumb: the QR code should be no smaller than 1/10 the expected scanning distance. A code expected to be scanned at arm's length (50cm) needs to be at least 5cm square. A wall-mounted code scanned from 1m away needs to be at least 10cm.
Minimum Size for Common Use Cases
Business cards: minimum 1.5cm × 1.5cm. Flyers and posters: 2.5cm or larger. Packaging (scanned at typical retail distance): 2cm minimum. Restaurant table tents (30cm away): 3cm. Always test before production — these are minimums, not targets.
Digital Resolution Requirements
For digital display, QR codes should be at least 300x300 pixels for screen use and 1000x1000 pixels for anything that might be printed. SVG format is preferable for any application where the size might vary.
Complexity Affects Minimum Size
QR codes encoding more data have higher module counts and require proportionally larger physical sizes. A QR code encoding 50 characters can be smaller than one encoding 300 characters while remaining scannable at the same distance. Keep encoded data concise.
Size your QR code for the expected scanning distance (1/10 ratio), generate at sufficient resolution, and test the actual print before production. Short URLs produce less complex codes that scan reliably at smaller sizes.