How small can a QR code be, and how far away can it be scanned?
The 10 to 1 rule for QR code size, the smallest a printed code should be, and what makes a code scan from across a room.
Utilica3 min read
A printed QR code should be at least 2 cm (0.8 in) wide, and about one tenth as wide as the distance people will scan it from. That is the whole rule. The rest of this post explains why, and what changes the numbers.
The 10 to 1 rule
Divide the scanning distance by ten and you have the smallest width that works reliably.
| Scanned from | Smallest width | Typical use |
|---|---|---|
| 20 cm (8 in) | 2 cm (0.8 in) | Business card, product label, receipt |
| 30 cm (1 ft) | 3 cm (1.2 in) | Flyer held in the hand, menu |
| 50 cm (20 in) | 5 cm (2 in) | Table tent, counter sign |
| 1 m (3.3 ft) | 10 cm (4 in) | Shelf sign, door sticker |
| 3 m (10 ft) | 30 cm (12 in) | Poster on a wall, food truck menu board |
| 5 m (16 ft) | 50 cm (20 in) | Window sign seen from the street |
| 10 m (33 ft) | 1 m (3.3 ft) | Banner, booth backdrop |
These are minimums for a code that holds a short link. Bigger is always safer.
How small can a QR code be before it stops working?
On paper, about 2 cm (0.8 in) square is the practical floor. Below that, phone cameras struggle to focus close enough, and small printing errors start to merge the dots.
What really sets the limit is the size of each dot, not the size of the whole code. A QR code is a grid of squares called modules. The simplest code is 21 by 21 modules, and the largest is 177 by 177. The more a code holds, the more modules it needs, and the smaller each one gets at the same printed size.
So two codes printed at the same width can behave very differently:
- A code holding a short link might be 25 by 25 modules, so each dot is big and easy to read.
- A code holding a long address with tracking tags might be 57 by 57, so each dot is less than half the size.
This is the main reason to use a dynamic QR code for anything small. It holds only a short address, so the grid stays coarse however long the real destination is.
How far away can a QR code be scanned?
As far as you are willing to print it big. Using the 10 to 1 rule, a 1 m wide code can be scanned from about 10 m. Codes on billboards and stadium screens work the same way, just larger.
Three things cut that distance down:
- Dense patterns. A busy code needs to be closer, or larger, than the table suggests.
- Low contrast. Pale colors or a busy photo behind the code shorten the range a lot.
- Light. Glossy finishes reflect light and dim corners hide it. Matte printing in good light scans from further away.
Leave a quiet border
Every QR code needs an empty margin around it, called the quiet zone. The standard asks for four modules of blank space on every side. Without it, the camera cannot tell where the code ends and your design begins.
In practice: never let text, a frame or the edge of a sticker touch the code.
Do logos make a code harder to scan?
A little. QR codes carry spare data, called error correction, so part of the pattern can be covered and the code still works. The highest level, H, can lose about 30% of the pattern and still scan. A logo in the middle uses up some of that spare capacity, so a code with a logo has less room for a smudge, a fold or a scratch.
Keep the logo to roughly a fifth of the code's width, and test it on more than one phone.
Test before you print
The quickest test: print one copy at the real size, stand where your customers will stand, and scan it with an older phone as well as your own. If both open it in a second, you are done.
Utilica runs a scannability check on every code before you download it, and warns you if the contrast, the logo or the density is likely to cause trouble. For the rest of the printing checklist, including file types, see how to print a QR code that scans every time.
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