How big should a QR code be on a poster

Start from distance, not format

An 11 x 17 poster in a narrow hallway is read from 3 feet; the same poster in a lobby is read from 10. The real scanning distance sets the size, using the 10:1 rule: code width = distance divided by 10.

On an 11 x 17 poster, a 4 to 5 inch code still leaves room for strong visuals. Past 6 feet, the code eats a lot of space: often a sign to bring the poster closer to people rather than enlarge the code.

Mounting height and placement

• Between 4 and 5.25 feet from the floor: where people naturally raise their phone.
• Not behind reflective glass in full sun: glare hides the code.
• Somewhere people can stop: nobody scans in the middle of a moving crowd.

Contrast and call to action

Posters are colorful; the code must stay dark on light. Put it in a white box with its 4-module margin instead of right on the photo. Write the expected action large, above or below: "Full schedule", "Save your seat". The designer's frames with call-to-action text handle this cleanly.

Files and large-format printing

Posters are usually printed large-format digital or screen printed: supply the code as vector (SVG, PDF or EPS) so it stays sharp at any size. A 1,000 pixel PNG printed 8 inches wide drops to about 125 pixels per inch, with visibly soft edges. For an outdoor poster in direct sun, ask for UV-resistant inks: a black that fades to gray in a few weeks kills the contrast. On a vinyl banner, wind warps the surface, so use error correction Q or H and go a bit bigger than the calculation. Before a large run, print one poster, hang it where it will live and scan it from the real distance with two different phones. That one test saves a reprint more often than any rule of thumb.

A poster that outlives the event

Posters often stay up for weeks after the date. With a dynamic code, point it to event photos, then to next year's edition. For events, the event QR code adds an "Add to calendar" button.

Common mistakes

1. A flyer code scaled up without math: 1.5 inches on a poster read from 6 feet, and nobody scans it.
2. A code placed on a photo: contrast drops and the margin disappears.
3. A poster hung too high above a display: phones cannot frame the code.

The size calculator gives the exact size by distance, density and colors.