B5 size: 176mm × 250mm。
The paper size is used by standardizing the length and width of the paper into a fixed proportional size. At present, the most commonly used internationally is the standard formulated by ISO, and the dimensions are numbered, such as A4, B5 and so on.
International standard paper sizes can be divided into three series: A, B and C. The characteristic of this standard is that the aspect ratio of paper size is √ 2 (about 1.4142). The geometric scale of the same series but different sizes of paper is the same, so it can be directly scaled and copied without causing the problem of edge cutting of paper pattern.
The basis for the formulation of series a is to obtain a sheet with an aspect ratio of √ 2 and an area of 1 square meter (M ²) Therefore, the width and length of this paper are 841mm and 1189mm respectively (the length width ratio is √ 2:1) , and the number is A0. If the long side of A0 paper is cut into two, two pieces of A1 paper with width and length of 594mm and 841mm will be obtained. If the A1 paper is cut in this way, the paper sizes of A2, A3, A4 and so on can be obtained in sequence. When formulating the standard, the sizes are all subject to integer, so if the paper size cut in half has decimal (less than 1mm), it will be rounded.
The basis for the formulation of Series B is to find that the length of the wide side is 1m and the area is √ 2 square meters (m) ²) Therefore, the width and length of this paper are 1000 mm and 1414 mm respectively (the length width ratio is √ 2:1) , and number it B0. If you cut the long side of B0 paper into two, you will get two pieces of B1 paper with width and length of 707mm and 1000mm. If you continue to cut B1 paper in this way, you can get the paper sizes of B2, B3, B4, etc. in sequence. Compared with series a, the paper area of Series B is √ 2 times that of series a with the same number, for example, the paper area of B4 is √ 2 times that of A4.
The formulation of Series C is based on the geometric average of the dimensions of Series A and series B. For example, the paper size of C4 is the geometric average of A4 and B4, and the paper aspect ratio is still √ 2:1. In this way, the size of C4 is between A4 and B4, and A4 paper can be loaded into C4 size envelope bag.