There is no so-called 4A paper, it should refer to A4 paper, which is subject to the paper size, and the general size is 2 10 * 297mm. Simply put, it is "A4" paper, that is, the paper with the basic size of Type A is folded in half for four times, so the area of an A4 paper is a quarter of the area of the basic paper, that is,116. The rest and so on.