Official 10:1 Optical Formula
QR Code Print Size & Distance Calculator
Never print a blurry or un-scannable QR code again. Calculate the exact dimensions in centimeters, inches, and pixels.
Optimal printed size
5.6 × 5.6 cm
(2.2 × 2.2 inches)
Where the 10:1 ratio actually comes from
You've probably seen a QR code that just did not work: someone printed it too small on a flyer, or shrank it down to fit in the corner of a poster where it was never going to scan from a few feet away. The reason is almost always the same: the code was sized for how it looked on a screen, not for how far away someone would actually stand when scanning it.
A phone camera reads a QR code by resolving its individual modules (the small black and white squares that make up the pattern). From close up, even a tiny code has plenty of resolution. Move further back, and those same modules start to blur together. The 10:1 rule (keep the code at least 1/10th the size of the distance it will be scanned from) is the industry standard baseline tested across phone cameras and ambient lighting conditions.
This calculator does the arithmetic for you: take the distance you expect people to stand at, divide by ten, and that is your floor. Then it adds about 25% on top of that floor for the "optimal" figure, because real scans rarely happen in ideal conditions.
Quick reference chart
The same 10:1 formula, applied to common print formats.
| Medium | Scan Distance | Minimum Size | Optimal Size |
|---|---|---|---|
Business Card | 25cm | 2.5 × 2.5 cm | 3.1 × 3.1 cm |
Restaurant Table Tent | 45cm | 4.5 × 4.5 cm | 5.6 × 5.6 cm |
Product Packaging Box | 35cm | 3.5 × 3.5 cm | 4.4 × 4.4 cm |
A4 / A5 Wall Poster | 1.2m | 12 × 12 cm | 15 × 15 cm |
Window Decal / Door | 2.0m | 20 × 20 cm | 25 × 25 cm |
Trade Show Rollup Banner | 3.0m | 30 × 30 cm | 37.5 × 37.5 cm |
Highway Billboard | 15.0m | 150 × 150 cm | 187.5 × 187.5 cm |
The 4 optical factors that dictate scannability
Distance is only part of the equation. Ensure your printed collateral accounts for these physical print and optical variables.
1. Data Density (Matrix Version)
A QR code encoding a short 20-character URL generates a low-density Version 2 matrix (25×25 grid) with large, bold modules. Encoding a lengthy 150-character URL packed with raw tracking parameters forces a Version 8 matrix (49×49 grid), cutting the physical size of each black square in half. High-density codes require 30% to 50% larger physical dimensions to maintain camera readability.
2. The Mandatory 4-Module Quiet Zone
The ISO/IEC 18004 specification mandates a clear, unprinted buffer zone around the entire perimeter of the code. This margin must measure at least four times the width of a single module. Cropping the quiet zone or placing background artwork right up against the finder eyes prevents mobile camera sensors from isolating timing tracks, resulting in scan failures.
3. Substrate Finish & Surface Curvature
Glossy laminate films, cellophane wraps, and metallic foils produce harsh specular reflections under direct spotlights, blinding optical sensors. Furthermore, placing a QR code around a cylindrical beverage can or cosmetic bottle compresses the outer timing patterns. For curved items, orient the code vertically or scale it up by 25%.
4. Ambient Lux & Color Luminance Contrast
Camera sensors require a minimum 4:1 luminance contrast ratio between foreground modules and the background substrate. Always print dark modules on a light background. Never invert a QR code (white modules on a black background) for physical print, as many default Android camera apps and budget smartphone sensors struggle to invert contrast in real time.
Pre-press production checklist for designers
Before approving high-volume packaging proofs or commercial offset print runs, verify your artwork against this pre-flight verification protocol:
- 1Export in Scalable Vector Format: Always supply your commercial printer with vector SVG or PDF files. Avoid pixelated PNG or JPG exports that risk raster anti-aliasing blur along module borders.
- 2Verify 100% K Black (CMYK): Ensure black modules are configured as pure 100% K (Key/Black) rather than 4-color rich black (C:75, M:68, Y:67, K:90). Rich black can cause color plate misregistration on high-speed presses, softening module edges.
- 3Preserve the Full Quiet Zone: Never allow bleed graphics, frame text, or packaging cut lines to infringe upon the 4-module quiet zone perimeter.
- 4Conduct Physical Proof Testing: Never test a code on an illuminated computer monitor. Print a physical 100% scale proof on the intended paper stock and test scannability from the maximum expected viewing distance across both iPhone and Android devices.
Frequently asked questions
A QR code should be printed at least 1/10th the size of its expected scanning distance. A code meant to be scanned from 1 metre away needs to be at least 10cm wide. Scan further back than that, and most phone cameras start to struggle to resolve the individual modules.