Most QR code failures are not technical. They are small decisions made in a hurry, usually the night before a print deadline. Here are the twelve that come up most, why each one breaks, and the fix.
1. Printing it too small
A code needs to be at least one tenth of the distance it is read from. A 3 cm code on a poster read from 2 m is one seventh of what it should be. Phones cannot focus on it, and the modules blur together. The size guide has the table.
Do this
A 20 cm code on a poster read from 2 m, with the URL printed beneath it.
Not this
A 3 cm code in the poster's corner because the designer thought it was ugly.
2. Encoding a long URL
Every character adds modules. A short link fits a version 3 or 4 code; a tracking URL with a session ID can reach version 8 or higher. At the same printed size the modules shrink and the code fails on cheaper cameras. Shorten the link or use a dynamic code.
Long URL
Short link
Do this
A 56-character short link at version 4.
Not this
A 148-character URL with five tracking parameters at version 8, printed at the same size.
3. No call to action
Nobody scans a bare square. A short instruction beside the code tells people what they get and why it is worth the effort. Scan for the menu. Scan to join the Wi-Fi. Scan to book.
Do this
Scan to see today's specials, printed above the code in the same type as the rest of the card.
Not this
A code in the corner of a leaflet with nothing beside it.
4. Linking to a PDF menu
A PDF is a fixed A4 page. On a phone it loads slowly, needs pinch-zooming and cannot be searched or translated. A simple mobile web page with the same items is faster, readable and easy to update. If the menu must be a PDF, keep it under 1 MB and test it on mobile data.
Do this
A one-page mobile menu that loads in two seconds and fits the screen.
Not this
A 14 MB print-ready PDF that takes ten seconds and opens as a tiny page.
5. Pointing at a dead link
The code is fine; the page has moved. Websites get redesigned, products are discontinued, campaign pages are taken down. The code on the shop wall stays. Check every live code at least every few months, and use a page you control rather than a campaign page that will be deleted. The dead code guide explains how to rescue one.
Do this
A code pointing at a stable page on your own domain, checked quarterly.
Not this
A code pointing at a seasonal landing page that was deleted when the campaign ended.
6. Letting a dynamic code expire
A dynamic QR code is a short redirect. If the subscription lapses or the service closes, every printed code stops working at once. Know which of your codes are dynamic, who pays for the service, and when it renews. Prefer a service that lets you export the code and the destination list.
Do this
Dynamic codes on a service with a renewal reminder and an export of every destination.
Not this
Codes made on a free trial in 2024, by someone who has since left, on a service nobody logs into.
7. Low contrast
The camera needs dark modules on a light background. Grey on white, pastel on cream and a gradient that fades to white all fail in the real world even when they scan on a bright monitor. Aim for a contrast ratio of 4.5 to 1 or better. The colours guide has the numbers.
Do this
Black or a very dark brand colour on white.
Not this
Mid-grey modules on a light grey background to match a minimal design.
8. Cropping the quiet zone
The quiet zone is the blank border around the code, four modules wide. It is part of the code, not padding. Designers crop it to save space, and then the corner squares merge into whatever sits next to them.
Do this
Four modules of clear background on every side, plus a margin before any text or border.
Not this
A code butted against a border line and a block of text.
9. Wrong placement
A code above a doorway, on a moving vehicle or behind reflective glass cannot be scanned however well it was made. Put it where a person can stand still, between 900 and 1500 mm from the floor, in even light. The placement guide covers each surface.
Do this
A code at hand height beside the till, where customers wait.
Not this
A code on the back of a bus, aimed at drivers in traffic.
10. Not testing it
A code that scanned on your monitor has not been tested. Print it on the real stock, at the real size, and scan it from the real distance with an old phone and a new one. The testing guide is ten steps and twenty minutes.
Do this
Printed a test sheet on the final stock, scanned it with two phones from the real distance.
Not this
Scanned the design on screen once, then approved 5,000 leaflets.
Common mistake
Testing only with the newest iPhone in the office. It has the best camera and the most forgiving software. The customer’s four-year-old Android phone in a dim restaurant is the real test.
11. Tracking without telling anyone
Counting scans is fine. Storing personal data about the person who scanned is not fine without a lawful basis and a notice. Say near the code what you collect, and turn off anything you do not need. The campaign tracking guide covers the options.
Do this
Scan counts by day and country, with a one-line notice and a link to the privacy policy.
Not this
A redirect service logging IP addresses and device fingerprints, mentioned nowhere.
12. No printed fallback
Some people cannot scan. Their phone is old, their camera is broken, the light is wrong or they simply do not know how. A short URL printed beside the code costs nothing and rescues every one of them. It also lets a cautious reader see where the code goes before scanning.
Do this
getqrstudio.app/menu printed in plain type under the code.
Not this
A code alone, so anyone who cannot scan it gets nothing.
Try it in QR Studio
QR Studio’s scannability audit catches numbers 1, 2, 7 and 8 before export. It warns when the module size is too small for the chosen print size, when contrast is low, and when the quiet zone has been cropped.
Checklist
- Code is at least one tenth of the scan distance
- URL shortened, or a dynamic code used
- Call to action printed beside the code
- Destination is a mobile web page, not a large PDF
- Destination is on a domain you control and is checked regularly
- Dynamic codes have a known owner, renewal date and export
- Contrast ratio 4.5 to 1 or better, dark on light
- Quiet zone of four modules kept clear
- Placed at 900 to 1500 mm, in even light, on a flat surface
- Tested printed, on two phones, from the real distance
- Tracking disclosed near the code
- Short URL printed as a fallback
Try it yourself
Upload the finished artwork. The tester shrinks it, blurs it and lowers the contrast, then tells you which of these mistakes it would survive.