Introduction of A4 paper
A4 paper is defined by ISO 216 of the International Organization for Standardization, with a specification of 21*29.7cm (210mm×297mm). The paper size used in most countries in the world adopts this international standard. This standard was originally included in DIN by the Weimar Republic in 1922 (the number is DIN 476). Although some of these formats were developed by France during the same period, they have forgotten afterward. ISO 216 defines three groups of paper sizes, A, B, and C. Group C paper sizes are mainly used for envelopes.
The aspect ratio of the paper sizes in Group A is √2:1 and then rounded down to the nearest millimeter value. A0 is defined as a paper with an area of one square meter and an aspect ratio of √2:1. The following paper sizes such as A1, A2, A3, etc. are all defined as folding the paper with the number one number less in half along the long side and then rounding it down to the nearest millimeter value. Group B paper size is the geometric average of Group A papers with the same number and one numberless. Before the popularization of printers, group B paper was mostly used. Group C paper sizes are mainly used for envelopes.
What are A4 paper and its size definition?
A4 paper can be said to be a kind of printing paper.
In order to facilitate the size of the printer, different types of paper are produced, which are slightly larger than 16K.
The specification of paper refers to that after the paper is made, it is trimmed and cut to a certain size. In the past, the size of the paper was expressed by the number of “opens” (such as 8 karats or 16 karats, etc.). Now international standards are adopted, which stipulate that the paper is represented by A0, A1, A2, B1, B2, etc. Format specifications. The standard stipulates that the ratio of paper width (indicated by X) and length (indicated by Y) is X: Y=1:n.
According to the basic area of the paper format, the format specifications are divided into A series, B series, and C series. The format size of A0 format is 841mm×1189mm, and the format area is 1 square meter; the format size of B0 is 1000mm×1414mm. The area is 2.5 square meters; the format size of C0 is 917mm×1279mm, and the format area is 2.25 square meters; the format specification of copy paper only adopts A series and B series. If the A0 paper is split into two equal parts along the length, it becomes the A1 size, and the A1 paper is split along the length direction to become the A2 size, so it is split to the A8 size; the B8 paper is also split to B8 according to this method. Specification. The format sizes of A0～A8 and B0～B8 are listed in the table below. Among them, A3, A4, A5, A6 and B4, B5, B6, and other 7 format specifications are commonly used specifications for copy paper.
For example “A4” paper is to fold the A-type basic size paper 4 times, so the area of a piece of A4 paper is one-fourth of the basic paper area, that is, 1/16. The rest can be deduced by analogy.
