Qraft

Aspect Ratio

Last updated:

Aspect ratio is the width-to-height proportion. QR codes are defined as square matrices (1:1) per ISO/IEC 18004. Finder pattern detection assumes square geometry - distorted aspect ratios cause recognition failure.

Finder patterns in a square 1:1 QR code compared with a horizontally stretched oneSquare 1:1 - scansStretched - fails to scan
Stretching the symbol leaves the three finder patterns no longer square, so detection fails.

Common distortion occurs when resizing QR code images in design software without locking aspect ratio. Always enable "constrain proportions" when resizing. Exception: rMQR (Rectangular Micro QR Code) is a variant designed for elongated spaces, but requires specialized decoders.

Which aspect ratios suit a QR code, and which do not.

Aspect ratioTypical useUse with a QR code
1:1 (square)The QR code symbol itselfThe shape defined in ISO/IEC 18004
4:3Older television screensStretched, so it fails to scan
16:9Widescreen videoStretched, so it fails to scan
Rectangular (rMQR)Narrow spaces such as labels, tubes and circuit boardsNeeds a decoder that supports rMQR