What you'll need to know v2018.09.24.1507
The Square logo is positioned under the headline, alingned to the 'N', not the text box, even if the headline changes to, say, NEW NEEDS YOU. The logo's height is 17% of the longest edge - for example the height of the logo on an A4 page would be 17% of 297mm = 50mm.
Paper size — Logo size
NB: Logo sizes have been rounded off.
It's almost impossible to allow for every format proportion, therefore use the 17% rule as a guide to working out the correct logo size. The equations works best for A-sizes i.e.. A5, A4, A3, A2, A1, A0.