Robert Bringhurst in his “The Elements of Typographic Style” devotes a whole separate chapter to the designing of a page – its format and proportion. Interestingly, the formats described in the ISO 216 standard, i.e. the conventionally used in the printing industry the A and B sizes, are, according to the author, the least harmonious among the most important page formats. An undeniable advantage is the fact that the sheet of 1: √2 proportions when folded in half gives us a sheet of the same proportion.
Paper sheets – ISO or other formats?
The A3, A4 and A5 sizes can be found in notebooks, sketchpads, office printing papers, etc. These are the optimum formats using standard paper sheets available in commerce, therefore justified economically. However, in more elegant books and publications the ISO formats are hardly used. This is probably because designers, people who have an artistic soul, often subconsciously sense their dissonance.