There are not many things in this world that I hate more than Letter Size paper.
Just look at it. Isn’t it horrible? Sitting there being based on outdated imperial units, looking all wonky and fat.
But instead of explaining in great detail why I hate Letter Size paper I’m going to explain why I love its main competitor: A4 size paper.
A4 is the fourth size in the metric International Standard (ISO 216) A-series of paper which runs from A0 (the largest) to A10 (the smallest). The A-series is constructed so that the longer side is 1.414 (√2) times the length of the shorter side, which makes each size in the series composed of two copies of the next-smallest size.
If x is the length of the shortest side then the area of an A-series sheet of paper is 1.414x2. Given that the first size in the series, A0, has an area of 1m2, that means that the short side of Ao is 841 millimetres and the long side 1189 mm. From this, the dimensions of all the remaining sizes in the series can be found.