It would be annoying for me to use paper with such strange dimensions. 8.5 x 11, 11 x 17, etc are much easier measurements for me to remember. The root 2 thing with European paper is pleasing though.
As a European, I have no clue what's the dimensions of A4, A5, etc. We just say A4. I don't think that laymen, like me, know anything about their real size, and I never had a problem not knowing it.
Its mathematically derived. A0 is exactly 1m2 in area. The side lengths are at a ratio of sqrt(2), that means you can cut any A paper size in half and get the size below it. B series are the same ratio, but B0 has a width of 1m instead.
If you fold A4 in half you get A5, and if you double up A4 you get A3. They are all the same exact proportions.
US sizes don't work like that; the closest thing to A3 here doesn't have the same proportions as the closest thing to A4. Which absolutely sucks if you are designing a poster and need to make it bigger or smaller.
With international A sizes you can reuse the same design for any size. That's why I like them.
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.
