▦QR Code Generator

The rule that decides whether a printed QR code works: make it roughly a tenth of the distance it will be scanned from.

A code on a poster read from two metres needs to be around twenty centimetres across. One on a business card held at thirty centimetres can be three. Most codes that fail in the field are simply too small for where they were placed, and nobody tested them at the actual distance.

The quiet zone

The empty margin around the code is part of the code. Placing it tight against other artwork, or letting a background pattern run into it, is one of the most common reasons scanning fails — and it looks fine on screen at 400 pixels wide.

Polarity is not interchangeable

Dark code on a light background scans reliably. The inverse fails on many readers, including some phone cameras. This catches out designers working on dark layouts, where inverting it looks obviously correct.

Shorter content scans better

More data means a denser pattern with smaller modules, which needs more resolution and better focus. Pointing a code at a short URL rather than a long tagged one produces a visibly simpler pattern — worth doing for anything printed small.

These are static

The destination is fixed once printed. If the target might change, point the code at a URL you control and redirect from there — that gives you a dynamic code without paying a service for one.

Commercial dynamic codes route through the provider’s servers and stop working entirely if you stop paying, which has stranded a lot of printed material.

Tell people what it is

A short line of text next to the code measurably increases how many people scan it. People are reasonably wary of unlabelled codes now, and rightly so.

Generated locally — the content is never sent to a server.