How big should a printed QR code be?

A QR code that nobody can scan is just decoration. Size is the most common reason a printed code fails, and it is easy to get right with one rule and a few checks.

The 10:1 rule

Make the code at least one tenth of the distance from which people will scan it.

Treat 2 × 2 cm as the absolute minimum, even for business cards. Go bigger when the code holds a lot of data: a long address or a full contact card makes the squares smaller at the same size. Dynamic codes help here, because they always hold a short link and stay simple.

Leave the quiet zone empty

Scanners need an empty margin around the code, called the quiet zone, of at least four squares (modules) on every side. Text, borders or a busy background inside that margin are a frequent cause of failed scans.

Four mistakes to avoid

1. Low contrast. Dark code on a light background works best. Light grey on white, or a pastel code on a pastel box, fails in poor light.
2. Inverted colours. A light code on a dark background is not read by every scanner. Test it on several phones before printing.
3. A logo that is too big. A logo in the middle relies on error correction. Keep it well under a third of the code width and use the highest error correction level.
4. Printing a low-resolution image. Use a vector file (SVG, PDF or EPS) for print, or a PNG of at least 1000 pixels. For offset printing ask for a CMYK PDF.

Test before you print thousands

Print one copy at the real size and scan it with two or three different phones, from the real distance and in the real light. With a dynamic code you can also open a temporary test link first, so test scans do not end up in your statistics.

Scanteo checks contrast, quiet zone, inverted colours and logo size while you design, and tests every style with two independent decoders before you download the file.