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The Difference Between A3 Sheet Size And A4 Sheet Size

A3 And A4 Sheet Size:

Nowadays printing has become a necessity for everyone. Not only in businesses or offices but printing is also used in every other household thus the need for printing is everywhere. When it comes to printing the most important thing is the paper on which you print. Different printing needs require specific types and sizes of papers. Paper comes in various classes and sizes and choosing the right one for your need brings up the question to understand the difference between the sizes. Below we will be looking at the A-series paper and the difference between the A3 size sheet and the A4 size sheet.


The international standard, also known as the ISO 216 standard, is used all over the world. It is built on an aspect ratio of the square root of two, like the side of a square and its diagonal. The A format is the most widely used all over the world. Many countries use A4 paper size as the standard sheet of paper. The sizes in the A series are the ones most used on a day-to-day basis. A-class paper is defined as paper with the correct ratios, which means it can be folded in half exactly to create the next smallest size. 

Math Behind A Series Paper:

All sizes ib A series are based on an aspect ratio which gives a proportion of 1.4142 (a / b = 2 b / a = √2). The square root of 2 is therefore the foundation of size A. This is what Professor of Physics Georg Christoph Lichtenberg explained to his friend Johann Beckmann in a letter dated October 25, 1786, written on a sheet that just used this ratio. This is the oldest record of a √2 ratio format. Mr.Lichtenberg is known as the father of A format.

Different Sizes of A Series:

Understanding paper sizes can be a bit confusing as it operates on a reverse scale where the largest dimension paper is labeled the smallest number. The A-series is currently used all around the world. The most common paper size used is A4, which is 210mm × 297mm (8.27 inches × 11.7 inches). 


A0 size of paper is the largest sheet from the A-series. It has an area of 1m2, and the dimensions are 841mm × 1189mm. The A-series uses a ratio of 1 aspect: in parallel with its smaller faces, the secondary sizes are defined in the series by plying paper in half. For example, cutting an A3 in half, will create two A4 sheets, and so forth. The A-Class series runs to a tiny A10 size. Below we will be looking from A0 to A4.

A0 Sheet Size:

Though it is the lowest in number but the largest among all. The paper size of A0 is  841 x 1189 mm. In height, it is over a meter and is equivalent to 16 pieces of A4 paper size. This is mostly used for making large signs and posters.

A1 Sheet Size:

A1 is smaller than A0, The paper size of A1 is 594 x 841 mm.  They are similar in usage to A0 paper. These paper sheets are used for creating signs, window displays, and posters.

A2 Sheet Size:

A2  scales down from A1. the  A2 paper size is 420 x 594 mm. This size of paper would be used for are notices, posters, art prints, and window displays.

A3 Sheet Size:

This paper form is mostly seen at work or school, A3 paper size is 297 x 420 mm. A3 Sheet Size of the paper is one of the more popular paper sizes around. This tends to be for posters, plans, charts, and presentations. While not as popular as A4 which is a go-to paper size for home use.

A4 Sheet Size:

It is the most common and known size of the paper, A4 paper size is 210 x 297 mm. Used throughout the world. It is used for everyday printing for everything from Word documents to stationery letterheads. This format is known as the universal home printing format. All laser and inkjet printers along with some mobile printers have the A4 capability.

Differentiating A3 and A4:

  • As explained earlier folding any of the A-series paper in half, parallel to its smaller sides gives two sheets of the next size. Therefore, one A3 sheet when folded in half makes two A4 sheets.
  • A3 size in millimeters is 297 x 420mm, in centimeters is 29.7 x 42.0 cm and in inches is 11.69 x 16.54”
  • A4 size in millimeters is 210 x 297mm, in centimeters is 29.7 x 21.0 cm and in inches is 8.3 x 11.7”
  • A3 paper is rarely used for home printing but it is widely used by various industry professionals for commercial use. It requires a dedicated printer that can accommodate this size (normal printers are limited to A4 size). 
  • A4 is the most known ‘A’ paper size and is commonly used for everyday printing. A4 is used for everyday printing for everything from Word documents to stationery letterheads. This format is known as the universal home printing format. 
  • A3 paper prints are the same as A4 paper printing. You should ensure the A3-size paper is suitable for your printer. Otherwise, the paper might not be properly loaded.
  • In recent years more and more individuals and small businesses have started using A3 size as it cuts the cost of printing.

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