QR Code Size Calculator

What it works out

How big a QR code needs to be printed for a given scanning distance, and what that means in millimetres, inches and pixels at your print resolution. It also reports the module size, which is the number that actually decides whether a printer can hold the detail.

Paste the real content

Size depends on how much data is in the code, so the calculator encodes the content you type and uses the resulting module count. A short link and a full vCard need very different sizes at the same distance. Change the error-correction level too — H adds redundancy and therefore modules.

The rule behind the number

The estimate uses the widely applied field rule that a phone can read a code from roughly ten times its width, tightened to eight for dense codes and relaxed to twelve for sparse ones. It is a planning heuristic, not a specification: real performance depends on the camera, the lighting, the substrate and how steady the hand is. Treat the output as a recommended estimate and test a printed sample.

Do not forget the quiet zone

The QR specification asks for four modules of clear space on every side. The calculator reports the size with and without it. Losing the quiet zone to a border, a fold or a busy background is one of the most common reasons a technically perfect code fails in the field.

The floor

Below about 20 mm across, phone cameras struggle regardless of the arithmetic — focus distance and sensor resolution stop cooperating. If the maths says 12 mm, print 20 mm.

Then test it

Print at the final size, on the final material, and scan with a few real phones including an old one. The testing guide sets out a repeatable routine worth following before any print run.