Among all the varieties of paper formats that exist in the world, A4 is the most common. It is on such sheets that standard printers are oriented. This format is used for printing documents, educational and scientific papers; writing statements and much more. What are the characteristics of this paper size?
Paper sizes A
A4 is a representative of the A line of formats. These are standardized paper sizes used in most countries of the world, introduced in the 1920s at the initiative of the German engineer and mathematician Walter Portsmann, one of the creators of the DIN standards system.
The aspect ratio for all sheets of this format ruler is the same - if the short side is taken as a unit, then the long side will be equal to the root of two (1: 1, 4142). If a sheet with such proportions is bent in half along the long side, then the resulting "halves" will have the same aspect ratios.
The maximum sheet size for ruler A is a sheet with an area of one meter (length of sides - 841 x 1189 mm). It was named A0. When folded in half, sheets of A1 are obtained, when folded again, A2, and so on. In fact, the digital index is equal to the number of folds that need to be made to get a sheet of a given format from A0, and the larger the number, the smaller the sheet.
The A Series is not the only international standard for paper sheet dimensions and proportions. There are also lines of formats B and C, but they are mainly dealt with by specialists in the field of printing. Their aspect ratio is the same, but the “reference points” are different - for sheets of B0 format, the length of the short side is equal to one meter (while for A0 it is only 841 mm). The dimensions of the sides of sheets of size C represent the geometric mean between A and B. It is this standard "with an allowance" that is used in the manufacture of envelopes for sheets from the common ruler A.
What is the size of A4 sheet
The height and width of a standard A4 sheet of paper are 297 and 210 millimeters (29.7 by 21 centimeters). Inches, the paper sizes of this metric-based ruler are usually not measured. However, knowing that one inch corresponds to 2.54 cm, it is not difficult to calculate the size of A4 sheet in these units. It will be 11.75 X 8.25.
Sizes of "neighboring" (and also quite common) formats:
- A3 (twice as much) - 420 by 297 mm;
- A5 (half as much) - 210 x 148 mm.
If you try to recalculate the sheet size yourself according to the principle "divide the length of the larger format by two and get the width of the smaller format", you may notice some discrepancy: dividing 297 by two should result in 148.5, while the width of the A5 sheet is 148 without any "halves". All odd quantities are divided in the same way. This “missing millimeter” is deducted “per cut”. At the same time, in accordance with GOSTs, sheets of paper may have a slight deviation from the "reference" dimensions - it should not exceed 3 mm.
How much does a pack of A4 paper and a separate sheet weigh?
The properties of paper are largely determined by its density, measured in grams per square meter - this indicator is equal to the weight of one sheet of A0 format. As office paper, material with a density of 80 g / m2 is most often used - and this indicator is optimal for most models of office equipment designed for paper with a density of 70 to 90 g / m2. Thinner paper is already considered writing, in office equipment it wrinkles and spoils the equipment.
The approximate weight of one sheet of ordinary A4 office paper is 5 grams, and a standard pack of 500 sheets of paper, in turn, weighs about 2.5 kg (deviations from this value for different manufacturers usually do not exceed 100-150 grams).
In order to calculate the weight of A4 sheet for paper of a different density, it is enough to divide the value of this indicator by 16 - after all, this is how many A4 sheets "fit" into sheet A0.
Characteristics of A4 office paper
Density is an important, but not the only characteristic of paper. Among other important criteria affecting the quality and perception of the text printed on it, there are also indicators of whiteness - the degree of approximation of the color of the paper to "absolutely white" and the level of opacity.
For office purposes, class C paper is usually used - it is the most common and is great for document management, copying, printing text materials, and so on. The whiteness of such paper is 92-94% according to the ISO scale (135-146% according to CIE), and the opacity is 89-90%. It is this paper with a density of 80 g / m2 that is most often sold under the name of office paper.
"Improved", smoother grade B paper costs a little more and is much less common. Its opacity is 91-92%, whiteness is also higher - 97-98% ISO, 152-160% CIE. It is commonly used in digital printers for high-speed and duplex printing, as well as color or laser copying for large print runs.
The least common office paper belongs to class A, and eucalyptus raw materials are used for its manufacture. The whiteness of such paper is not lower than 98% according to ISO and from 161% according to CIE, and the cost is almost twice as high as that of standard packs of class C.
The class of office paper and its density are usually indicated on the package of the pack - and the whiteness and opacity of a particular brand can be found in the specifications for the product, A4 white paper of classes A, B, C or in the descriptions of goods provided by online stores.
How many pixels in A4 format
It is impossible to say exactly how many pixels "fit" in A4 format - after all, a pixel does not have its own "dimension", and how clear and detailed an image is depends on the number of pixels per inch. Accordingly, the number of pixels in the image, which can be completely, without borders, "seal" A4 sheet will depend on the resolution of the picture. You can calculate it, knowing the dimensions of A4 in inches (11.75x8.25) and the dpi of the image (the number of pixels per inch).
So, at a resolution of 72 dpi, the size of the sheet will correspond to a picture with 846 pixels on the long side and 594 on the short side. With a resolution of 300 dpi, which allows you to get a fairly clear and high-quality image when printing, you will need a 3525 x 2475 pixel image. In total, such an image should contain 8.7 megapixels.