Short answer
A common rule of thumb is to make a QR code about one tenth as wide as the scanning distance: 1 metre away needs about 10 cm, and a business card read at 20 cm needs about 2 cm. Longer content means more modules, so check that each module stays above roughly half a millimetre.
How the calculator works
- It builds the real QR code for your content at the error correction level you chose, so the module count is exact rather than estimated.
- It divides your scanning distance by 10 to get a code width, with a floor of 2 cm.
- It divides the width by the module count to get the size of a single module, and flags anything under 0.5 mm.
- It adds the four-module quiet zone on each side and converts the total to pixels at 300 dots per inch.
The 0.5 mm warning line is our own rule of thumb, chosen because phone cameras at arm's length start missing modules smaller than that on matte paper. It is not from a standard. Good printers and good light do better; cheap inkjet on glossy stock does worse.
Quick reference
| Where | Distance | Code width (10:1) |
|---|---|---|
| Business card, label | 15–25 cm | 2–2.5 cm |
| Menu, flyer in hand | 30–50 cm | 3–5 cm |
| Table tent, counter card | 50–80 cm | 5–8 cm |
| Shop window, wall sign | 1–2 m | 10–20 cm |
| Poster across a room | 3 m | 30 cm |
| Banner, stage screen | 5 m and more | 50 cm and more |
If the numbers come out uncomfortable, shorten the content first. A short URL to a square page is always smaller than a vCard with an address in it. Then raise contrast, and only then make it bigger. More in the print guide.
Questions
Where does the 10:1 rule come from?
It's an industry rule of thumb used by printers and QR vendors, not part of the QR standard. Phone cameras vary, and lighting, angle and print quality matter as much as size. Treat it as a starting point and test a printed proof at the real distance.
Why does my content change the size?
More characters need more modules. At the same printed width, a code with 57 modules a side has modules less than half the size of a 25-module code, and small modules are harder to focus on. Shorter links give you bigger modules.
Does the quiet zone count in the width?
The calculator gives both. The code width is the dark pattern itself; the quiet zone adds four modules of blank margin on every side, and that margin must stay clear on the printed piece.
What resolution should I export?
For print, use SVG when you can. If you need PNG, aim for at least 300 pixels per inch of printed width including the quiet zone. The calculator shows that number.