How Big Should a QR Code Be?
The 10:1 sizing formula, density adjustments, DPI requirements, contrast rules, and a complete size table for every print format from business cards to billboards.
By Kerron Gordon, IT Instructor & Network Technician
A QR code that doesn't scan is worse than no QR code at all — it's a broken experience and wasted print budget. Whether you're placing a code on a business card or a highway billboard, the scan success rate is determined by math and contrast, not luck. This guide gives you the formulas, the size table, and the material-specific traps to check before sending anything to press.
The 10:1 rule for sizing
The most common question about QR codes is: "How big should it be?" The answer depends entirely on one thing — how far away the person scanning it will be.
The formula
Minimum QR Code Width = Scanning Distance ÷ 10
This is the standard from the QR code specification (ISO/IEC 18004). A phone camera held 10 inches from a 1-inch code produces the same relative image as a phone held 10 feet from a 1-foot code. The ratio is what matters, not the absolute size.
Size table by print format
| Format | Scanning distance | Min. size (imperial) | Min. size (metric) |
|---|---|---|---|
| Business card | ~10 in | 1 × 1 in | 25 × 25 mm |
| vCard on business card | ~10 in | 1.5 × 1.5 in* | 38 × 38 mm* |
| Flyer / A5 brochure | ~12 in | 1.25 × 1.25 in | 32 × 32 mm |
| Restaurant table tent | ~20 in | 2 × 2 in | 50 × 50 mm |
| A4 poster | ~24 in | 2.4 × 2.4 in | 60 × 60 mm |
| Storefront poster | ~50 in | 5 × 5 in | 127 × 127 mm |
| Exhibition banner (2m) | ~40 in | 4 × 4 in | 100 × 100 mm |
| Highway billboard | ~720 in (60 ft) | 72 × 72 in | 1,830 × 1,830 mm |
* vCard and other dense codes need 50% more than the base formula because their matrix has more modules.
Data density: the factor the 10:1 rule doesn't account for
The 10:1 rule assumes a simple code with modest data — a short URL, a WiFi password, plain text. The more data packed into a static QR code, the more modules (tiny squares) the matrix uses, and the smaller each module becomes relative to the total code size.
A vCard QR code encoding a full name, title, company, mobile number, email, and website URL creates a substantially denser matrix than a short URL code. At small print sizes, the individual modules in a dense code can blur together in the camera sensor before it can decode them — particularly on phones with lower-quality cameras or in poor lighting.
Dense code rule
To reduce density, reduce the amount of data encoded. For a vCard, the most effective reduction is removing rarely used fields: fax numbers, multiple phone numbers, physical addresses, or long notes. Each removed field meaningfully reduces the matrix complexity.
DPI requirements for print
DPI (dots per inch) defines the print resolution of a raster image file. The standard for commercial print work is 300 DPI. A QR code PNG intended for print needs to be sized so that it achieves at least 300 DPI at the final print dimensions.
The formula: required pixel dimensions = print size in inches × 300.
- A 1-inch QR code printed at 300 DPI requires a source file of at least 300 × 300 pixels.
- A 2-inch QR code requires at least 600 × 600 pixels.
- A 5-inch QR code requires at least 1,500 × 1,500 pixels.
GetEasyQR exports a 1024 × 1024 pixel PNG. At 300 DPI, this produces a print-ready file for sizes up to approximately 3.4 × 3.4 inches. For anything larger, use the SVG export if available, or request your designer scale from the vector source.
Never scale a raster PNG up beyond its native resolution — you'll introduce blur at the module edges, which the scanner may fail to resolve. A 300 × 300 pixel PNG scaled up to fill a 5-inch space at 300 DPI looks like a pixelated block to a camera. Use vector formats for large-format work.
Contrast rules
The QR scanner reads contrast between dark and light areas. It identifies the finder patterns (the three large corner squares) by looking for a specific 1:1:3:1:1 ratio of dark and light modules. If contrast is insufficient, the scanner can't locate those patterns, and the code fails before the data is even attempted.
Good contrast
- Black on white (most reliable)
- Dark navy on white
- Dark green on pastel yellow
- Dark brown on cream
- Any pairing with at least 60% luminance difference
Poor contrast
- White on black (inverted) — fails on many Android devices
- Light grey on white
- Navy blue on dark background
- Similar-saturation complementary colours
- Gradient backgrounds behind the matrix
The quiet zone
The blank border surrounding the QR code is not padding — it's a functional requirement. ISO 18004 specifies a minimum quiet zone of four modules on all four sides. The scanner needs this white space to distinguish the boundary of the code from whatever else is on the page.
In practice, "four modules" translates to roughly 1–3mm at typical business card print sizes. It's small enough that designers often reduce it without realising, either by cropping the PNG in their layout software or by placing design elements too close to the code. If you open the exported PNG in Adobe InDesign, Canva, or Figma and scale or crop it, check that the white margin on all four sides is intact in the final layout.
Physical material traps
Frequently asked questions
Generate a print-ready code
GetEasyQR exports a 1024 × 1024 lossless PNG with a full quiet zone included. Free, generated in your browser.
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