How to make a QR code that actually scans

A QR code is a picture of some data. Whether a camera can read it comes down to contrast, size, and how much you asked it to carry — and printing a thousand flyers is an expensive place to find out.

Codes fail in the field far more often than people expect, and essentially never because the generator was bad. They fail because of decisions made before printing.

Keep the data short

More characters means a denser grid of smaller squares, and small squares are what cameras struggle with. A long tracking URL stuffed with parameters can double the density of the pattern compared with a short link to the same place.

Shortening the destination before you generate is the single cheapest way to make a code readable from further away.

Contrast, size and the quiet zone

• Dark pattern on a light background. Inverted codes fail on many scanners and low-contrast colour pairs fail on most.
• Keep the white margin around the code. Scanners use it to find the edges, and cropping it off is a common reason a working code stops working.
• Never place a code over a photograph or a gradient.
• Size to the distance: roughly one tenth of the scanning distance. Two centimetres for something held in the hand, thirty for a code read from three metres.

Logos and error correction

QR codes carry redundant data, which is why a logo in the middle works at all. Raising the error correction level allows a larger logo but makes the pattern denser, so the two settings pull against each other. Past roughly a fifth of the code covered, you are gambling.

Making one

1. 1Open the QR Code Generator and choose what the code should hold — a link, a WiFi network, an email address, a phone number or plain text.
2. 2Style it if you want, keeping the contrast strong.
3. 3Download it at a size comfortably larger than you need. Scaling down is safe; scaling up is not.
4. 4Test it before it goes anywhere — from the medium it will appear on, at the distance people will stand.

Test with more than one phone if the code is going to print. Camera apps differ more than you would expect, particularly on older devices.

The one thing you cannot change later

A static QR code has its destination encoded in the pattern itself. Once printed, it points where it points, forever. If there is any chance the destination will move, point the code at a short link you control and change where that link goes instead.

Putting a code into a document rather than onto a poster? Download it, then place it with Add Text to PDF or include it when you assemble the pages.

Common questions

Do QR codes expire?

The code itself does not — it is just a pattern encoding data. What expires is the destination, if the link it points at stops working.

What size should I print a QR code?

About one tenth of the scanning distance. Two centimetres works in the hand; a code read from three metres away needs around thirty.

Can I use a generated QR code commercially?

Yes. The QR format is an open standard and codes you generate are yours to use.