Guide
What size should a QR code be?
One rule covers most cases: the code should be about one tenth as wide as the distance it will be scanned from. Everything else is refinement.
Print a QR code at roughly one tenth of the intended scanning distance: 30 mm for arm's length, 300 mm for three metres. The absolute minimum for reliable scanning is a module size of 0.4 mm, which for a typical URL code means about 20 mm square.
Ten to one
Scan distance is about ten times the code width. It is an approximation that holds well across phones, because it reflects camera resolution and focus behaviour more than any single device.
| Scan distance | Minimum width | Comfortable width | Typical placement |
|---|---|---|---|
| 10 cm | 10 mm | 20 mm | Business card, product label |
| 30 cm | 30 mm | 40 mm | Menu, flyer, table tent |
| 1 m | 100 mm | 120 mm | Poster, shop window |
| 3 m | 300 mm | 350 mm | Estate agent board, A-board |
| 5 m | 500 mm | 600 mm | Building signage |
| 10 m | 1000 mm | 1200 mm | Billboard, stadium screen |
Use the comfortable column. The minimum assumes a good camera, good light and a person who stops walking.
The number that really decides it
Width alone does not determine scannability — module size does. A dense code printed at 30 mm can have smaller modules than a sparse code at 20 mm, and it is the sparse one that scans.
module size = code width ÷ (modules across + 8)The +8 accounts for the four-module quiet zone on each side.
| Module size | Reliability |
|---|---|
| Under 0.3 mm | Fails on most phones |
| 0.3 – 0.4 mm | Marginal — good print and good light only |
| 0.4 – 0.5 mm | Reliable, the practical floor |
| 0.5 – 1.0 mm | Very reliable, standard for print |
| Over 1.0 mm | Excellent, and required for signage |
The live readout in the generator shows the minimum recommended print width for the exact code you are building, based on its real module count.
Two levers before you resize
If a code is too big for the space, do not just scale it down. Reduce what it has to encode:
- Shorten the content. A 90-character URL with tracking parameters is a version 5 code. The same link at 25 characters is version 2 — modules nearly twice the size at the same printed width.
- Lower the error correction from H to M, if the code is not going somewhere it will be damaged. That can drop a version or two on its own.
- Drop optional fields from vCards and Wi-Fi payloads. The address line on a vCard is often 40 bytes for information nobody uses.
- Only then consider whether the space can grow. It usually can, by a few millimetres, and that is cheaper than an unscannable print run.
When to go bigger than the rule says
- Moving audience. Anything scanned from a car, a train platform or a walkway needs 50% more than the table suggests.
- Poor lighting. Dim restaurants, car parks and evening signage. Add 25%.
- Absorbent stock. Newsprint, kraft, uncoated card. Add 10–15% for ink spread.
- Angled viewing. Codes high on a wall or low on a plinth are read at an angle, which effectively shrinks them.
- Older audience. Older phones and steadier-but-slower framing. Bigger is kinder.
- Behind glass or laminate. Reflection loses effective contrast; size compensates a little.
Frequently asked
What is the minimum size for a QR code?
How big should a QR code be on a poster?
Does a bigger QR code scan faster?
How do I make my QR code smaller without breaking it?
Last reviewed 24 August 2026 · Written and reviewed by the QR Code Builder team