A QR code that looks perfect on your laptop can fail on a poster, a shop counter or a visiting card. Almost every scanning problem comes down to five things: size, distance, the white border, contrast and the amount of data. Get these right and your code will scan first time on almost any phone.
1. Size: how big should a QR code be?
A useful rule of thumb is that the code should be about one tenth of the scanning distance. If people will scan from 1 metre away, make the code around 10 cm wide. Some practical minimums:
- Visiting cards and small labels: at least 2 × 2 cm, and 2.5 cm or more is safer.
- Table tents, menus and counter stands: 4 to 6 cm.
- Shop windows and A4 posters: 10 to 15 cm.
- Banners and hoardings seen from several metres: 30 cm or more.
When in doubt, go bigger. Nobody has ever complained that a QR code was too easy to scan.
2. Data: shorter content scans better
The more characters you put in a code, the more tiny squares (called modules) it needs, and the smaller each square becomes at the same print size. A short link such as yourshop.in/menu makes a simple, bold pattern. A long link with tracking parameters makes a dense pattern that needs to be printed much larger.
- Remove tracking text after the
?in a link if you don't need it. - For a contact card, include only the details people really need.
- If you must encode a lot of data, increase the print size to match.
3. The quiet zone: keep a white border
Scanners need an empty margin around the code to find its edges. This margin is called the quiet zone, and it should be at least four modules wide (four of the little squares). Don't let text, borders or photos touch the code. A common mistake is placing a code right at the edge of a card or on top of a busy photo.
4. Contrast and colour
- Dark dots on a light background work best. Many phones struggle with light dots on a dark background (an “inverted” code).
- Colour is fine if it is dark enough. Navy, dark green, maroon and deep purple all scan well on white or cream. Yellow, light grey, pastel pink and sky blue often don't.
- Gradients look great, but keep both ends of the gradient dark.
- Avoid shiny laminates and glossy paper under bright lights. Reflections can hide part of the code. Matte finish is safer.
The Apna QR generator warns you with “Hard to scan with this style” when your colours or shapes are likely to cause problems.
5. Logos and error correction
QR codes have built-in error correction, which lets them be read even when part of the pattern is damaged or covered. There are four levels: L (about 7% can be recovered), M (about 15%), Q (about 25%) and H (about 30%). When you add a logo in the middle, you are deliberately covering part of the code, so a higher level is used.
- Keep the logo small, roughly a fifth of the code's width or less.
- Never cover the three big squares in the corners. Scanners use them to find the code.
- A logo on a plain white circle or square scans better than a logo that blends into the dots.
PNG or SVG?
- PNG is perfect for WhatsApp, websites, presentations and most home or office printing. Download a large size for printing.
- SVG is a vector file. It stays perfectly sharp at any size, from a business card to a hoarding. Print shops and designers prefer it.
Never stretch a code unevenly or save it as a small, blurry JPEG. Both can make it unreadable.
Test before you print hundreds
- Print one copy at the real size, on the real paper.
- Scan it with at least two phones, including an older or cheaper one.
- Try it from the distance and in the light where people will actually scan it, such as a dim restaurant or a sunny shop front.
- Check that the result is correct: the right link opens, the right Wi-Fi joins, the right UPI name appears.
This takes five minutes and can save a whole print run.
Checklist: big enough for the distance, short content, a white border on every side, dark dots on a light background, a small logo, and a real-world test before printing.