Guide · updated November 4, 2026
QR code
guide
Static or dynamic, print size, colors, logo, security: what to know before you print a QR code, explained simply.
What a QR code is
A QR code ("Quick Response") is a square barcode invented in 1994 by Denso Wave, in Japan. Its black and white squares, called modules, store text: most often a web address, but also Wi-Fi details or a contact card. The three large squares in the corners let a phone find the code at any angle.
Part of the pattern is redundant, so a QR code can still be read when it is slightly damaged or partly covered. This is the error correction level: L (about 7 %), M (about 15 %), Q (about 25 %) or H (about 30 % of the code can be restored).
Static or dynamic
| Static QR code | Dynamic QR code | |
|---|---|---|
| What it contains | The content itself (address, Wi-Fi, contact) | A short address that redirects to your content |
| After printing | Cannot be changed | You change the destination whenever you like |
| Statistics | None | Number of scans, date of the last scan |
| Works without the internet | Yes, for Wi-Fi or contact details | No, the redirect needs a connection |
For anything printed that may change (a menu, a promotion, a page address), choose a dynamic QR code: you will never have to reprint because a link changed. Watch out for generators that switch dynamic codes off after a free trial. A Paynelia free QR code is dynamic and keeps working for life.
What a QR code can open
- A link
- Wi-Fi access
- A restaurant menu
- A contact card
- Google reviews
- A business page
- An event
- A lost item tag
- A pet tag
- A child safety tag
A Wi-Fi QR code is always static: the phone reads the network name and password and connects directly. A contact card can be static (the details are in the code) or dynamic (the details stay editable).
Print size
The right size depends on the scanning distance. A common rule of thumb: 1 cm of QR code for every 10 cm of distance.
| Where | Scanned from | Suggested size |
|---|---|---|
| Business card, label, tag | 10 to 20 cm | 2 to 2.5 cm (about 0.8 to 1 in) |
| Flyer, table tent, menu | 20 to 40 cm | 3 to 4 cm |
| Counter sign, A4 poster | 50 cm to 1 m | 5 to 10 cm |
| Shop window, large poster | 1 to 3 m | 10 to 30 cm |
The longer the content, the denser the pattern and the bigger the code must be. A dynamic QR code has a short address, so its pattern stays simple and reads well even small.
Colors, logo and frame
- Dark on light. Dark dots on a light background read everywhere. Light dots on a dark background are refused by some readers.
- Enough contrast. Pale yellow, light grey or pastel shades often fail. Choose a dark shade for the dots and the corners.
- A small logo. A logo in the center works when the error correction is high (H). Keep it small and test.
- A call to action. A frame that says what the scan does ("Scan me", "Our menu", "Free Wi-Fi") gets more scans than a bare code.
Which file for which use
| File | Best for |
|---|---|
| SVG | Vector: stays sharp at any size. For designers, large formats, websites. |
| PDF (CMYK) | For printers: vector, in the color mode used by printing presses. |
| PNG | For screens, documents and social media. Download it large enough for your use. |
Test before printing
- Scan the final file with at least two phones, an iPhone and an Android if you can.
- Print a proof at real size and scan it from the real distance, in the real light.
- Check that the page it opens works well on a phone.
- Glossy finishes and curved surfaces cause reflections: test on the final material.
Security
Fake QR codes stuck over real ones, on parking meters or posters, are used to steal payment details. When you scan, read the address your phone shows before opening it. Never enter a password or bank details on a page reached from a QR code you are not sure about.
When you create QR codes for your business, use a generator that checks destinations. Paynelia refuses short links that hide the real address and lets anyone report a suspicious QR code from its scan page.
Create my free QRFree email signature
QR code FAQ
Do QR codes expire?
A static QR code never expires: the content is written into the pattern itself. A dynamic QR code works as long as the service that redirects it keeps it active. Some generators switch QR codes off after a trial; a Paynelia free QR code keeps working for life.
What is the minimum size to print a QR code?
Around 2 cm (0.8 in) per side for a code scanned from close up, like on a business card. For a poster or a window, use the rule of thumb of 1 cm of QR code for every 10 cm of scanning distance, and always test the printed proof.
Can I put my logo in the middle of a QR code?
Yes, as long as the QR uses a high error correction level (H, about 30 %) and the logo stays small. Always test the result with several phones before printing.
Can I change the link of a printed QR code?
Only if it is a dynamic QR code. The printed pattern points to a short address, and you change the destination behind it. A static QR code has to be reprinted.
Is it safe to scan a QR code?
Most are, but fake QR codes stuck over real ones exist. Check the address your phone shows before opening it, and never enter a password or bank details on a page you reached from an unknown QR code.
Which phones can read a QR code?
Recent iPhones and Android phones read QR codes directly with the camera app, with no extra app needed.