148x210 A5 297x210 A4 297x420 A3 Agree, I had to look it up as well. I can memorize A4 and A3 easily, but A5 is already counter-intuitive. It's an aspect ratio

148x210 A5 297x210 A4 297x420 A3 Agree, I had to look it up as well. I can memorize A4 and A3 easily, but A5 is already counter-intuitive. It's an aspect ratio that's kept, so that's why the numbers don't add up easily. With the paper in front of me it's easier, fold, double, you can navigate across all levels of A(n) quickly. All it takes is seeing this single graphic for a split second and you know all the DIN A-sizes, but the US sizes not. I enjoy the US Letter format though as a size, it feels somehow better than A5 as it's more square. https://en.wikipedia.org/wiki/Paper_size#/media/File:A_size_illustration2_with_letter_and_legal.svg https://en.wikipedia.org/wiki/Paper_size#/media/File:A_size_...