QR codes that still work in five years

Restaurants have reprinted menus because their QR codes stopped working. Not because the paper wore out — because the free service behind the code moved the feature to a paid tier. This is the most expensive thing people do not know about QR codes.

Static versus dynamic

A static code contains the destination itself. The URL, the Wi-Fi password, the contact card — encoded directly into the black and white pattern. Scan it and your phone reads the data straight out of the image. Nothing else is involved, so nothing else can fail.

A dynamic code contains a short link belonging to the generator, which redirects to your real destination. That buys you two things: you can change the destination after printing, and you get scan analytics. It also means your printed material depends permanently on that company staying online, staying free, and staying in business.

Most free generators produce dynamic codes without making that obvious, because the redirect is where their business is.

Get both without the dependency

You do not have to choose between editability and independence. Generate a static code pointing at a URL on a domain you control — yoursite.com/menu — and change where that page redirects whenever you like.

You keep the ability to update the destination. You keep the analytics, in your own server logs. And nobody else can switch it off. The QR generator here produces static codes only, for exactly this reason.

Four rules for printing

Leave the quiet zone. The blank margin is not decoration — scanners use it to find where the pattern starts. Four modules is the specification. Cropping it tight is the single most common cause of a code that will not scan.

Size it against the reading distance. The code should be at least one tenth of the distance it is read from. Read from 30 cm on a flyer, print at 3 cm. Read from 3 metres on a poster, print at 30 cm. Never below 2 cm on paper.

Use SVG for print. It is a vector, so it stays perfectly crisp at any size. A PNG scaled up in a layout program produces soft edges that confuse scanners.

Test on real phones, on the real material. Print one proof at final size and scan it with an old Android and a current iPhone, in the lighting where it will live. Glossy laminate under a spotlight defeats codes that scan perfectly on screen.

Error correction, briefly

QR codes carry redundant data so they survive damage. L recovers about 7%, M about 15%, Q about 25%, H about 30%. Higher is not automatically better — redundancy makes the pattern denser, and a denser pattern must be printed larger. M is right for most jobs. Move to Q or H for outdoor signage, packaging, or when placing a logo over the centre.

Design limits worth respecting

Brand colours are fine if you keep contrast above roughly 4:1 and keep the pattern darker than its background — inverted codes are technically valid but many scanner apps will not attempt them. Avoid gradients and photographic backgrounds behind the pattern. And leave the three corner squares alone: those finder patterns are how a scanner locates the code, and restyling them measurably reduces scan rates on older devices.