Give your code
room to be read.

How the calculation works

REHAU's print guideline uses code width equal to scanning distance divided by 10. We use that as a practical starting rule, not a scanner specification. DENSO WAVE recommends at least 4 printer dots per module and a quiet zone at least 4 modules wide on every side.

The calculator takes the larger of the distance-based width and the print-density width, then rounds up to a whole printer dot per module. A QR version has 17 + 4 × version modules per side. Add twice the quiet zone, then multiply by the module size. DPI converts to millimeters using 25.4 mm per inch.

A worked example

With the example inputs of a 30 cm scanning distance, version 3 and a 300 DPI printer, the distance rule starts at 30 mm. The symbol has 29 modules; the margin makes the full width 37 modules. At 10 printer dots per module, the rounded width is 31.33 mm. These are calculated examples, not measured scan performance.

Keep the final code square and include its full blank border. Test a proof on the actual material, at the intended distance. If the reader hesitates, increase the size, shorten the payload or simplify the design.