How to use the QR Off-Axis Scan Calculator
How this calculator works
A flat code seen from an angle presents a narrower width to the viewer: the width the scanner sees is the printed width times the cosine of the viewing angle. The recommended width reverses that: dividing by the cosine gives the printed size that presents the width you originally planned. The height is unchanged, so the code appears squeezed, which is exactly what makes angled codes hard to scan.
Where off-axis viewing happens
Signage on walls beside a walking route, codes on pillars, and posters at the end of a corridor are all read at an angle. The angle that matters is the one from the viewer’s actual position, not from directly in front of the sign — measure it where people really stand.
Fixing an angled code
The honest fixes are a bigger code, a better position, or a second code facing the approach path. Uplifting the size helps up to a point, but beyond about 60 degrees the foreshortening is so severe that repositioning beats enlarging. Test at the real angle with an ordinary phone before committing to a large print.