Printing paper refers to a kind of paper used to print and copy documents. Specifications are A0, A1, A2, B1, B2, A4, A5, etc.

The specification of paper refers to that after the paper is made, it is trimmed and cut into a certain size. In the past, the size of the paper was expressed by the number of "open" (such as 8 open or 16 open). I adopted the international standard, which stipulates that the format specification of the paper is represented by A0, A1, A2, B1, B2, A4, A5, etc. The standard stipulates that the proportional relationship between the width (expressed in x) and the length (expressed in Y) of the paper is X: y = 1: n.

According to the basic area of paper format, the format specifications are divided into a series, B series and C series. The format size of A0 is 841mm × 1189mm, with a width area of 1m2; The format size of B0 is 1000mm × 1414mm, with a format area of 2.5m2; The size of C0 is 917mm × 1279mm, with a width area of 2.25m2; The format specification of copy paper only adopts series a and series B. If A0 paper is split into two equal parts along the length, it becomes A1 specification, and if A1 paper is split along the length direction, it becomes A2 specification, so it is split to A8 specification; B8 paper is also opened to B8 specification according to this method. The dimensions of A0 ~ A8 and B0 ~ B8 are listed in the table below. Among them, 7 format specifications such as A3, A4, A5, A6, B4, B5 and B6 are commonly used for copy paper.