How big should your QR code be?
Enter your scan distance and content to get the minimum printable size — in mm, inches, and pixels. The 10:1 sizing rule, module density, and quiet zone are all built in.
The 10:1 rule for QR code sizing
Every major QR scanning library — and the ISO/IEC 18004 standard itself — assumes a minimum width of 1/10th the viewing distance. At 30 cm (a typical arm's length), that's a 30 mm (3 cm) minimum. Print the code any smaller and most phone cameras will struggle to resolve the individual modules.
The rule is a floor, not a ceiling. Dense content forces a higher QR version with more modules. When the minimum module size (0.5 mm for reliable inkjet print) multiplied by the total module count exceeds the 10:1 result, density becomes the binding constraint — which is what our calculator tells you and why it matters.
| Use case | Scan distance | Min size (10:1) | Notes |
|---|---|---|---|
| Business card | 15 cm | 15 × 15 mm | Often 20 × 20 mm for safety |
| Flyer / leaflet | 50 cm | 50 × 50 mm | ~A6 card corner fits well |
| Poster (A1) | 2 m | 200 × 200 mm | ~20 cm square is comfortable |
| Billboard | 20 m | 2000 × 2000 mm | 2 m square — use dynamic QR |
All minimum sizes assume a typical URL at ECC M and 0.5 mm minimum module size. Use the calculator for exact figures.
Why dense QR codes need to be bigger
A QR code is a grid of black-and-white modules. Short content (like a 20-character URL) fits in Version 1 — a 21×21 grid. Long content (a 500-byte vCard) may require Version 15 or higher — a 77×77 grid with three times as many modules per side.
Each module must be large enough for a phone camera to reliably resolve it. Modern inkjet printers can hold modules down to about 0.5 mm. Cheap laser printers or laser-engraved materials need 1.0 mm or more. Multiply the module floor by the total module count (including the 4-module quiet zone on each side) and you get a minimum physical size driven purely by data density — independent of scanning distance.
The two constraints — distance and density — combine as a maximum: your code must satisfy both. The calculator shows which rule is binding for your inputs and flags when density wins so you know why. The honest fix when density is the problem: use a short dynamic QR link — your destination URL stays editable and scannable at a fraction of the version.
Frequently asked questions
What is the minimum QR code size?
The minimum QR code size depends on how far away the scanner will be. As a rule of thumb, the code should be at least 1/10th of the scanning distance — so 2 × 2 cm (about 0.8 × 0.8 in) works for arm's-length scanning (~20 cm). Dense content (long URLs, vCards) requires a higher QR version with more modules, which increases the minimum size further.
How big should a QR code be on a poster or billboard?
For a poster viewed at 2 m, the minimum is ~20 × 20 cm. For a billboard at 20 m, that grows to ~200 × 200 cm (2 × 2 m). The 10:1 rule applies at all scales: minimum size (mm) = viewing distance (mm) ÷ 10. Use the calculator above to get exact figures for your scenario.
What is the quiet zone on a QR code?
The quiet zone is a mandatory border of empty white space surrounding the QR code — 4 modules wide on all four sides. Without it, scanners can't distinguish the code edge from the background and will fail to read it. The calculator shows you exactly how many millimetres of quiet zone to leave based on your module size.
Does error correction level change the QR code size?
Yes. Higher error correction (Q or H) stores redundant data so the code survives damage or a logo overlay — but it increases the number of modules, which raises the minimum physical size. Level M (15% recovery) is the industry default for most use cases. Use H if you're adding a logo, knowing the code will need to be slightly larger as a result.
How do I make a QR code that stays small?
Keep the destination URL short. A full, long URL forces a higher QR version (more modules → bigger code). The easiest solution is a dynamic QR short link — you get a short branded URL that fits in Version 1–3, and you can change where it points after printing. See our dynamic QR codes for details.
Related tools & guides
Before you scan an unknown code, run it through our QR code safety checker.
Now make the QR code
You know the right size. Now create the actual code — free, no account needed.