# QR codes on posters

> A poster QR code is read from between one and three metres, so under the ten-to-one rule it needs to be 10–30 cm wide. Most posters carry codes at 3–5 cm, which is why most poster codes go unscanned.

Source: https://useqr.app/qr-codes-on/posters · Last reviewed 2026-08-21 · UseQR is free forever, MIT licensed, no signup.

---

| Typical scan distance | **1–3 m** |
|---|---|
| Minimum code width | **10–30 cm** |
| Error correction | **M** |

## The numbers

| Viewing distance | Minimum code width |
|---|---|
| 1 m (a corridor poster) | 10 cm |
| 2 m (a wall at eye level) | 20 cm |
| 3 m (across a lobby) | 30 cm |

That is the *code*, not the frame or the caption. On an A3 poster a compliant code occupies
roughly a quarter of the sheet — which is exactly why designers shrink it, and exactly why
it then fails.

## The real constraint is dwell time, not size

Nobody stops in a corridor to scan a poster. The codes that work are where people already
wait: a lift lobby, a bus shelter, a queue, a toilet door. Put a code where the audience is
stationary for thirty seconds and a 10 cm code outperforms a 30 cm one on a wall people walk
past.

## Height matters more than people think

Centre the code at **1.4–1.6 m** from the floor. Above 1.8 m the scan angle exceeds about
40° for anyone standing close, and steep angles are where decoding fails first.

## Print notes

- **Matt** stock. Gloss under downlighting produces specular reflection across the whole
  code, and no error-correction level survives that.
- Print from **SVG or PDF**, never an upscaled PNG.
- Error correction **M** is right. Codes this large have huge modules; H just wastes area.
- Give the four-module quiet zone real white space — poster designs habitually crowd it.

## Try it

- https://useqr.app/url
- https://useqr.app/size-calculator
- https://useqr.app/validate