Posters: Designed to Be Read at a Distance
Posters live on walls, in windows, and on notice boards, and they are scanned from wherever the viewer happens to stand — typically 1 to 3 meters away. Unlike a flyer, you cannot count on the viewer stepping closer; the code must work from the farthest reasonable viewing position, not the nearest. Poster scanning is also a one-shot affair: a viewer who tries, fails, and walks away is gone for good.
The 10:1 Rule of Thumb
Divide the farthest expected scanning distance by ten. A poster in a café viewed from 1.5 m needs at least a 150 mm code as a rule of thumb; a notice-board poster that people read from 3 m needs roughly 300 mm. When in doubt, round up — an oversized code on a poster looks intentional and confident, while a too-small one looks broken and gets ignored. Remember this is guidance for typical conditions; dim hallways and older phones both argue for going larger.
Recommended Size
For a standard A2 poster (420 × 594 mm) viewed from about 1.5 m, print the code at 150 × 150 mm (about 6 inches). For A1 or larger formats in lobbies, transit areas, and exhibition halls, scale proportionally to the farthest viewer distance. On a crowded notice board where viewers stand shoulder to shoulder at 1 m, 100–120 mm can suffice — but only if the lighting is good and the URL is short.
Substrate and Printing
Posters are usually printed on 200 gsm satin paper by large-format inkjet or offset, sometimes with a matte laminate for durability. Matte finishes are preferable for the code area: glossy lamination turns into a mirror under spotlights and kills contrast when viewed at an angle. For outdoor posters, UV-stable inks or a protective laminate are mandatory — sun and rain will fade an unprotected code within weeks, long before the campaign ends.
Placement and Practical Tips
- Posters behind glass (transit shelters, framed notice boards) need extra size — reflections force the camera to work harder, so add 20–30% to the rule-of-thumb size.
- Place the code at a comfortable standing height and away from the poster's edges; codes tucked into corners get cropped by frames or hidden behind neighboring posters.
- Keep the quiet zone clear of the poster's background imagery. A code floating on a busy photograph needs a solid light panel behind it.
- Link to a mobile-friendly page. Poster traffic is entirely phone-based — a desktop-only site wastes every scan.
- If the poster promotes a dated event, make sure the link stays live through the event date plus a grace period.
Common Mistakes
- Sizing for the designer standing 50 cm away in the studio instead of the viewer 2 m away in the hallway.
- Busy photographic backgrounds bleeding into the quiet zone, especially on music and event posters.
- Long URLs creating dense symbols that fall apart at poster-viewing distances — use a short redirect.
- Mounting the poster where a door swing, plant, or furniture blocks the code at scanning height.