QR Code Size Guide
How big should a QR code be? A practical look at the relationship between print size, scan distance and reliability.
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Size follows scan distance
The key rule of thumb: the further away people scan from, the bigger the code must be. A widely used guideline is a 10:1 ratio — the scan distance should be no more than about ten times the width of the code. A 2 cm code suits arm's-length scanning; a billboard needs a code many centimetres wide.
On-screen sizing
For codes shown on a screen, make sure they're displayed crisply and large enough that a second phone can capture them. Avoid scaling a small raster image up, which blurs the modules.
Print sizing
For print, don't go below roughly 2 cm (0.8 in) square for close-range scanning, and scale up for posters and signage. Use vector SVG so the code stays sharp at any size (see the printing guide).
Data density matters too
More data means more modules, and more modules mean each module is smaller at a given print size. If you must encode a lot, either enlarge the code or shorten the data. Our generators warn you when content is getting dense.
Quiet zone
Always keep the empty margin around the code — typically four modules wide. It doesn't count toward the "readable" area but it's essential for reliable scanning.
Always test
No formula guarantees a scan in every environment. Print a proof at the final size, on the final material, and test it with several phones before you commit.
Distance to size, at a glance
The working convention is that a phone camera reads a QR code from about ten times the code's width. Inverted, the code needs to be about a tenth of the intended scanning distance.
| Scan distance | Minimum width | Recommended | With quiet zone |
|---|---|---|---|
| 10 cm | 20 mm | 25 mm | ~31 mm |
| 30 cm | 30 mm | 35 mm | ~43 mm |
| 50 cm | 50 mm | 60 mm | ~74 mm |
| 1 m | 100 mm | 120 mm | ~149 mm |
| 2 m | 200 mm | 240 mm | ~297 mm |
| 5 m | 500 mm | 600 mm | ~743 mm |
The "recommended" column adds roughly 20% over the bare minimum, because the ten-times figure assumes good light, a steady hand and a modern camera. The quiet-zone column adds the four clear modules ISO/IEC 18004 requires on each side — on a typical 33-module symbol that is about 24% more width, and it is the figure to reserve space for in a layout.
Note the floor: below about 20 mm nothing works reliably, whatever the distance calculation says. Fixed-focus and older phone cameras cannot resolve modules that small.
Density changes the answer
Two codes the same physical size are not equally readable. A code holding a 25-character URL might be 25 × 25 modules; the same code holding a 300-character vCard could be 65 × 65. At 30 mm wide, that is 1.2 mm modules against 0.46 mm — a factor of nearly three in what the camera has to resolve.
| Content | Typical modules | Ratio to use | At 30 mm, module size |
|---|---|---|---|
| Short URL (~25 chars) | 25 × 25 | 12:1 | 1.20 mm |
| Normal URL (~60 chars) | 33 × 33 | 10:1 | 0.91 mm |
| Long URL with tracking (~120) | 49 × 49 | 10:1 | 0.61 mm |
| vCard contact card | 65 × 65 | 8:1 | 0.46 mm |
| Wi-Fi with long password | 37 × 37 | 10:1 | 0.81 mm |
Shortening the content is usually cheaper than enlarging the code. Dropping a tracking query string from a URL can take a symbol from 49 modules to 33 — the same physical size with modules half again as large. That is the single most effective thing you can do for a code that has to be small.
Aim to keep printed modules at 0.6 mm or above for public use. Check yours in the size calculator, which reports module size in millimetres alongside the overall dimensions.
Screens are measured differently
The ten-times rule applies to physical size on the display, not to pixels. A code 300 pixels wide is about 79 mm on a typical 96 dpi monitor but only about 25 mm on a high-density phone screen — a threefold difference from the same file.
For a code on a slide, a shop display or a TV: measure the rendered code on the actual screen with a ruler and work from that number. Allow extra for viewing angle — a code at the edge of a wide display is read obliquely, which costs effective resolution — and remember that screen brightness and glare both reduce effective contrast.
Written and maintained by the QRBarcodeTools Editorial Team · Last reviewed 2026-08-12 · How we write and check these guides