QR Code Size and Scanning Distance: A Practical Reference
A QR code that scans perfectly on a business card may be unreadable on a billboard. The relationship between code size, scanning distance, and module count determines minimum print dimensions for reliable scanning.
Key Takeaways
- As a rough guideline, the scanning distance is approximately 10 times the QR code width.
- A QR code's version determines its grid size.
- The quiet zone (empty border around the code) must be at least 4 modules wide for QR codes.
- Print a test code at the intended size on the intended material.
- Each module must be large enough for the camera to resolve it.
QR Capacity Reference
The 10:1 Rule of Thumb
As a rough guideline, the scanning distance is approximately 10 times the QR code width. A 3 cm code scans at about 30 cm (arm's length). A 30 cm code scans at about 3 meters. This ratio assumes a standard smartphone camera with autofocus in adequate lighting.
Factors Affecting Scan Distance
Module Count (Version)
A QR code's version determines its grid size. Version 1 is 21×21 modules; version 40 is 177×177 modules. Each module must be large enough for the camera to resolve it. A version 40 code needs to be physically larger than a version 1 code for the same scanning distance because its modules are proportionally smaller.
Contrast and Lighting
Low contrast (gray on white, or dark blue on black) reduces effective scanning distance by 30-50%. Direct sunlight creates glare on glossy surfaces. Backlit codes (printed on translucent material with light behind) scan at greater distances than reflected-light codes.
Camera Quality
Modern smartphones (2022+) have autofocus cameras that scan QR codes at greater distances than budget phones or older models. Design for the lowest common denominator in your audience.
Size Recommendations by Application
| Application | Scanning Distance | Minimum Code Size |
|---|---|---|
| Business card | 10-20 cm | 2×2 cm |
| Product label | 15-30 cm | 2.5×2.5 cm |
| Table tent (restaurant) | 30-50 cm | 3×3 cm |
| Poster (A3) | 50-100 cm | 5×5 cm |
| Banner/sign | 1-3 m | 15×15 cm |
| Billboard | 3-10 m | 50×50 cm |
| Building/vehicle wrap | 10-30 m | 1.5×1.5 m |
Quiet Zone Requirements
The quiet zone (empty border around the code) must be at least 4 modules wide for QR codes. At small print sizes, designers are tempted to reduce this margin to save space. This is the most common cause of scan failures on small codes. Never compromise the quiet zone.
Testing Protocol
Print a test code at the intended size on the intended material. Scan it at the intended distance with 3+ different devices. Test in the actual lighting conditions of the deployment environment. A code that scans in your well-lit office may fail in a dimly lit restaurant.