Measurements with give or take 0,5mm margin of error.

The whole QR box:
- portrait      3,3cm x 3,3cm
- horizontal   4,1cm x 4,1cm

QR code only:
- portrait       2,85cm x 2,85cm
- horizontal    3,5cm x 3,5cm

Priv Key (string)
- portrait       9cm x 0,65cm
- horizontal     11,1cm x 0,9cm
The whole box should be covered as sometimes different keys have different lengths but they all fit in the box; so better to have a sticker that covers the whole length of the box..