A4 Paper Size

A4 size is one of the paper sizes in the ISO A series, which was defined by ISO216 and first put forward by German scientist Georg Christoph Lichtenberg as DIN476 standard of Germany and later adopted by ISO. Under the same standard, there is also B size series, which follows the same rule as A series: ratio of length to width of a piece of paper should be √2:1.

A4 is the most well-known and widely used paper size in the A-series format. It is the standard size for most printed documents around the world, from letters and reports to academic papers and official correspondence. Its popularity in offices, schools, and homes is due to its perfect balance of portability and space for text and images, making it the go-to choice for everyday printing tasks.

Dimensions

A4 measures 8.27 x 11.69 in inches, 210 x 297 in mm, or 21.0 x 29.7 in cm.

It is precisely half the size of A3 when folded or cut, in line with the A-series system, which is based on halving each paper size in succession. A4’s dimensions make it ideal for general document printing, being neither too large nor too small, and it is perfectly suited for both text-heavy and image-based documents.

Physically, a piece of A4 paper can be folded twice to fit fully into a C6 envelope.

Layout

The figure below shows A4 dimensions in inches and mm. In cm it is 21.0 x 29.7cm, dividing its dimensions in mm by 10.

Origins

Like all A-series paper sizes, A4 was developed under the DIN 476 standard in 1922 by the German Institute for Standardization (DIN). The system aimed to create a simple, logical approach to paper sizes, ensuring each size was exactly half the size of the next largest format. The ISO 216 standard later adopted this system internationally, including A4 as the most common paper size for everyday use outside of the U.S.

Regions

As in the scope of ISO paper size standard, A4 is used in nearly every country outside the United States and Canada. It is the standard paper size for official documents, correspondence, and printing in most of Europe, Asia, Africa, and Oceania. Countries such as the UK, Germany, Japan, and Australia all use it as the default paper size in government offices, schools, and businesses.

In the United States, however, A4 is not as common, as the Letter size (8.5 x 11 inches) is the standard for most paper-based tasks. Despite this, A4 is used in the U.S. for international correspondence, legal documents, and by organizations that work with countries that follow the ISO paper standard.

Usage

Like its North American alternative the letter size, A4 paper is incredibly versatile and is used in nearly every field. Some of the most common uses include:

• Business Documents: A4 is the most common size for official correspondence, including letters, memos, contracts, and business reports.
• Educational Papers: In schools and universities, A4 is the standard size for assignments, research papers, essays, and exam papers.
• Magazines and Brochures: Many small-format publications, such as magazines, newsletters, and brochures, are printed on A4 paper, as it is large enough to include a variety of content but still easy to handle.
• Books and Manuals: While larger books may use different paper sizes, A4 is commonly used for smaller reports, manuals, instruction guides, and training materials.
• Personal Use: For everyday printing tasks such as letters, invoices, and personal documents, A4 is the paper size most commonly found in home printers and personal offices.

The size has become so ubiquitous that it is often assumed as the default size for documents and printing needs outside of the United States.

A4 Size in Inches

8.27″ x 11.69″

Inches are not the preferred unit for expressing the size of ISO paper size, as most of the countries where ISO standard is popular are metric volume-using countries. However, inches are used in order to give imperial size countries a better understanding of the size and an idea of its magnitude. Its format and dimensions in inches make it versatile, fitting easily into standard printers, binders, and document folders.

A4 Size in cm

21.0cm  x 29.7cm

The metric-based system of centimeters offers a precise and universally recognized measurement, making it ideal for businesses, governments, and educational institutions around the world. The dimensions in centimeters are a bit more intuitive in countries that use the metric system. The size is often used for both digital and printed materials, from official documents to creative projects, due to its perfect balance of usability and convenience.

A4 Size in mm

210mm x 297mm

This is the most detailed and accurate way to describe dimensions, as millimeters provide a finer level of precision compared to centimeters or inches. The metric measurement in millimeters is used in many fields such as engineering, design, and manufacturing, where exact dimensions are crucial. The dimensions in millimeters are particularly important for precise digital printing, where even small variations in size can affect the final output. In countries that follow the metric system, millimeters are the standard unit for paper dimensions.

A4 Dimensions Table

A4 Dimensions in Pixels

The dimensions vary in pixels, depending on the PPI/DPI applied.

* PPI (pixels per inch) = DPI (dots per inch) = Resolution

A Series Paper Size

The dimension aspect ratio of an ISO216 paper is √2:1, the A series paper size start from the first size, the A0 size.

Cut an A0 sized paper symmetrically at the midpoint of its long edge, you will get two A1 papers; then cut the papers you got in the same way, you will get 4 pieces of A2 sheets, and then 8 pieces of A3 sheets, and then 16 pieces of A4 sheet in the fourth cutting. Based on this scale, each size from A0 to A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, etc, is twice the one of the next code.

The figure below reflects the relationship between the dimensions of ISO paper size A, as well as letter size (8.5″ x 11″, wider and shorter) and legal size (8.5″ x 14″, wider and longer).

A4 Size vs. Letter Paper Size (8.5×11 paper size)

In the United States, Letter size (8.5 x 11 inches) is the standard for almost all office and personal documents. While Letter size, which measure is slightly wider than A4 (8.5 inches vs. 8.27 inches) and slightly shorter (11 inches vs. 11.69 inches), the difference is minimal.

The Letter size is essentially the U.S. alternative of A4, and both sizes are used for most business, educational, and personal printing tasks. However, in countries using the ISO system, A4 is the clear standard, and many U.S.-based companies that interact globally prefer it for international correspondence and official documents to ensure uniformity.

A4 is NOT the Same as Letter Size

Though the difference between A4 and Letter Size is small, they are not the same thing. The difference can cause minor issues when printing or formatting documents across systems using different paper standards. The discrepancy between the two is one of the reasons that documents may not print as intended when switched between paper types.

Again,

  – A4:  8.27″ x 11.69″
Used in non-North American countries, belongs to ISO A paper sizes

  – Letter Paper Size:  8.50″ x 11.00″
Specifically called ANSI A paper size, or American Quarto, used in North America, Mexico, the Philippines, etc, is part of the ANSI paper standard of US paper sizes

The Most Popular Paper Size in the World and Why

In non-American standard countries where ISO standard paper sizes are applicable, there are also many kinds of paper sizes to choose from. For example, Series A has sizes from A0 to A10 or even A12; The B series has sizes with the same principle. However, A4 paper is chosen as the most commonly used and for two reasons:

1. The most cost-effective size

This is not based on its material, but the ease of procurement and its wide applicability. At the same price, A4 paper is the paper with largest size that you can buy, on which you can print the most words and consume less for the same article, so in essence it is the most cost-effective for printing and copying.

For example, A5 size paper is only half of A4’s, but in some countries the copying price is higher than half of its; A3 size paper is twice as expensive as A4, but the copying price is high than double of its, so actually A4 is currently a dessert price charged for copying. Therefore, it naturally becomes the most widely used size in the world.

2. The ergonomic size

From the practical point of view, the size of A4 (8.27″ x 11.69″ in inches, 210 x 297 in mm, or 21.0 x 29.7 in cm) is just one of the most suitable dimensions for ergonomic comfort angle, whether it is used for writing or carrying.

Of course, there must be a size range that is most suitable for ergonomics, and fortunately A4 is exactly in this range and right the size specified by international standards. It should be noted that in North American countries, Mexico, the Philippines and other former colonial areas of the United States, people use letter paper size more as the office size, which measures 8.5″ x 11″ and is very close to A4, is just in this size range too.

In addition, from the perspective of dialectics, the more popular A4 is, the more corresponding manufacturers there are; and the mature technology and intensified competition make its production cost and selling price reach the most reasonable level, thus A4 becoming the best choice for people’s daily use.

The Size of Most Consumed Paper on The Planet and How

A4 Paper consumption: a shocking astronomical figure

Compared with any other size of paper in the world, A4 paper is the most widely used. Most countries and regions in the world use it as the main consumed paper, as much as hundreds of thousands of tons every day, which is a shocking astronomical figure.

Paper consumption and deforestation

A research published in the journal Nature in September 2015 proposed the answer of how many trees are cut down for paper products every year: 15.3 billion trees. By the time this page is being updated by me today in 2024, perhaps that number had increased a lot. What is certain is that among them, a considerable part comes from the consumption of A4 paper.

Therefore, taking good use of the paper on your desk, not wasting it, is the protection of nature. It is also the responsibility of each of us.

Here you can find the dynamic paper consumption status and Hectares of forests cut down of this year.

Main Facts

• A4 Dimensions in inches, mm, cm
  in inches: 8.27″ x 11.69″
  in mm: 210 x 297 mm
  in cm: 21.0 x 29.7 cm
• Area: 1/16 square meter.
• Country of use: Most countries except North America
• Other name: DIN A4
• Usage: Office paper in most countries in the world.
• Advantages: Suitable size for office and document signing, easy binding and carrying; No customization required, can be used in most countries internationally.
• Disadvantages: Not suitable for use in American countries.
• Ratio: It follows the ratio of ISO216 size standard, length to width: 1.414:1, or √2:1.
• Approximate American size: Letter paper size, measures 8.5″ x 11″ in inches, 216 x 279 in mm, or 21.6 x 27.9 in cm, and is slightly wider and shorter than the A4 size.

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