The 10:1 rule
QR code width ≥ scan distance ÷ 10.
Scanned from 30 cm (a hand-held flyer)? The code needs ≥3 cm. From 3 metres (a wall poster)? ≥30 cm. From 20 metres (a billboard)? ≥2 metres. Everything below is that rule applied.
Minimum sizes by placement
| Placement | Typical scan distance | Minimum code size |
|---|---|---|
| Business card | 20–25 cm | 2 × 2 cm |
| Product label / packaging | 25–30 cm | 2 × 2 cm (2.5 preferred) |
| Flyer / brochure | 30 cm | 2.5 × 2.5 cm |
| Menu / table tent | 30–40 cm | 3 × 3 cm |
| Counter display | 50 cm | 5 × 5 cm |
| Window decal | 1 m | 10 × 10 cm |
| Wall poster | 2–3 m | 20–30 × 20–30 cm |
| Projected slide | room-depth | 1/10 of the room's depth |
| Vehicle wrap | 3–5 m (stopped!) | 30–50 cm |
| Billboard | 15–25 m | 1.5–2.5 m |
Never go below 2 × 2 cm (0.8 × 0.8 in) in print, no matter how close the reader.
Data density changes the math
The 10:1 rule assumes a normal code (a short URL, ~25–30 modules across). Dense codes need MORE size:
- Long URLs, vCards, long text create 40+ module grids — add 30–50% to every minimum above, or better: shorten the content. A dynamic QR's short redirect keeps the grid sparse no matter how long the destination URL is.
- Logo in the center? Error correction level H makes the grid slightly denser — round sizes up. See logo rules.
Resolution and format for print
- Print: use SVG. Vector scales from a stamp to a billboard with zero quality loss. QRolling exports SVG free.
- If PNG is unavoidable: ≥300 DPI at final size. A 3 cm code needs ≥360 px; a poster code needs thousands.
- Screens: PNG is fine — 240 px+ for web, larger for retina.
- Keep the quiet zone (white margin ≥4 modules) — it counts as part of the required size, don't crop it.
Testing before mass printing
Print one sample at final size on the final material. Scan with an iPhone and an Android, from the real distance, in the real lighting — straight-on and at 30°. Then do it again with an older phone if your audience skews that way. Two minutes of testing beats 10,000 misprinted flyers. If the sample fails, run the not-working checklist.
How to size a QR code in 4 steps
Estimate the scan distance
Where will the reader stand? Hand-held is ~30 cm; posters are metres away. When unsure, take the farthest realistic distance.
Apply the 10:1 rule
Divide the distance by 10 — that's your minimum code width. Never below 2×2 cm in print.
Adjust for density and logo
Long content or a center logo? Add 30-50% or shorten the data. Export SVG for print.
Test at final size
One sample print, two phones, real distance and lighting — before the full print run.
Frequently asked
What is the minimum size for a QR code in print?
2 × 2 cm (0.8 × 0.8 in) for close-range scanning, assuming a normal-density code with good contrast. Denser codes (long URLs, vCards) need 2.5-3 cm minimum.
How big should a QR code be on a poster?
Use the 10:1 rule — one tenth of the viewing distance. A poster read from 3 metres needs a ~30 cm code. When in doubt, bigger never hurts scans; smaller always risks them.
What DPI does a printed QR code need?
300 DPI at final printed size if you must use PNG. Better: export SVG (vector) and DPI stops mattering entirely.
Does the white border count toward the size?
The quiet zone (≥4 modules of clear margin) is required for scanning and sits around the measured code size. Never crop it, and don't let design elements invade it.
Why does my small QR code scan on-screen but not in print?
Screens are backlit and pixel-perfect; print adds ink bleed, texture, and ambient light. That margin of error is exactly why print minimums exist — reprint at 2×2 cm or larger from an SVG.
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