How big does a QR code need to be?
A QR code that cannot be scanned is worthless. The most common reason: it was printed too small. But how large does a QR code actually need to be – and does it depend on the medium?
The short answer: yes, it depends. The rule of thumb is:
Minimum size = 1/10 of the scanning distance
If someone scans the code from 10 cm away, you need at least 1 cm. If it needs to be read from 10 metres, you need at least 1 metre.
Recommended sizes by medium
| Medium | Typical reading distance | Recommended minimum size |
|---|---|---|
| Business card | 10–20 cm | 2 × 2 cm |
| Flyer (A5/A4) | 20–40 cm | 2.5 × 2.5 cm |
| Brochure / catalogue | 30–50 cm | 3 × 3 cm |
| Poster (A3/A2) | 50 cm – 1 m | 4 × 4 cm |
| Large poster / banner | 1–5 m | 10 × 10 cm or more |
| Outdoor advertising / billboard | 5–20 m | 50 × 50 cm or more |
| Screen / presentation | 1–3 m | 5 × 5 cm |
| Packaging / product label | 10–30 cm | 2 × 2 cm |
Why 2 × 2 cm as an absolute minimum?
Modern smartphone cameras are good – but not infinitely so. Below 2 × 2 cm it becomes difficult even for current iPhones and Android devices, especially when the code contains a lot of data (long URLs, vCard information).
Furthermore: the more data in the code, the denser the pattern – and the larger it needs to be to scan reliably.
The quiet zone – the invisible factor
Almost as important as the size is the white border around the code, known as the quiet zone. Without this border, the scanner cannot distinguish the code from its surroundings.
The quiet zone should be at least 4 modules wide – where a module is the smallest unit of the QR code (the small black squares). In practice, at 2 cm size this is roughly 1–2 mm on each side.
Common mistake: The code is printed flush to the edge of a sticker or card – without any white space. This causes some scanners to fail to recognise it.
Reduce data = smaller code possible
If you know the code will be printed small, it helps to keep the URL as short as possible:
- Instead of
https://www.your-domain.com/products/category/item-name?id=12345, usehttps://your-domain.com/p/12345 - URL shorteners like bit.ly or your own short URL
A code with a 30-character URL has a significantly less dense pattern than one with 150 characters – and will scan more reliably at the same physical size.
Which download format to use?
Always use SVG for print – not PNG. SVG is vector-based and scales without any loss to any size. A PNG created for 3 cm and scaled up to 30 cm will be blurry and pixelated.
If your print layout does not support SVG: export PNG at the highest possible resolution (at least 1000 × 1000 pixels, ideally 2000+).
Colour and contrast – underestimated factors
Even a perfectly sized code can fail if the contrast is off:
- Minimum contrast: 4:1 between foreground and background
- Dark code on light background is the most reliable combination
- Light code on dark background sometimes works, but less reliably
- Colourful codes: Possible, but contrast must be right – test thoroughly
- No colour gradients in the background directly under the code
Conclusion
The minimum size for most applications is 2 × 2 cm. Anything smaller is risky. Always maintain a white border, use SVG for print, and test the code on real devices before the final print run.
QRHero.de exports your code in SVG and PNG – free, without registration.