Paper size

International paper sizes

The international paper size standard is ISO 216. It is based on the German DIN 476 standard for paper sizes. ISO paper sizes are all based on a single aspect ratio of square root of 2, or approximately 1:1.4142. There are different series, as well as several extensions.

The following international paper sizes are included in Cascading Style Sheets (CSS): A3, A4, A5, B4, B5.

A series

The base A0 size of paper is defined as having an area of 1 m² and a side ratio of 1 by √2, making the A0 paper size exactly 2 4  m × 1 2 4  m. Rounded to the nearest millimetre, that is 841 by 1,189 millimetres (33.1 in × 46.8 in).

Successive paper sizes in the series A1, A2, A3, and so forth, are defined by halving the preceding paper size across the larger dimension. This also effectively halves the area of each sheet. The most frequently used paper size is A4 measuring 210 by 297 millimetres (8.27 in × 11.7 in).

The significant advantage of this system is its scaling: if a sheet with an aspect ratio of √2 is divided into two equal halves parallel to its shortest sides, then the halves will again have an aspect ratio of √2. Folded brochures of any size can be made by using sheets of the next larger size, e.g. A4 sheets are folded to make A5 brochures. The system allows scaling without compromising the aspect ratio from one size to another—as provided by office photocopiers, e.g. enlarging A4 to A3 or reducing A3 to A4. Similarly, two sheets of A4 can be scaled down and fit exactly on 1 sheet without any cutoff or margins.

The behavior of the aspect ratio is easily proven: on a sheet of paper, let a be the long side and b be the short side; thus, a/b = √2. When the sheet of paper is folded in half widthwise, let c be the length of the new short side: c = a/2. If we take the ratio of the newly folded paper we have:

b c = b a 2 = 2 a b = 2 2 = 2

Therefore, the aspect ratio is preserved for the new dimensions of the folded paper.

Weights are easy to calculate as well: a standard A4 sheet made from 80 g/m² paper weighs 5 g (as it is  ¹⁄₁₆ of an A0 page, measuring 1 m²), allowing one to easily compute the weight—and associated postage rate—by counting the number of sheets used.

The advantages of basing a paper size upon an aspect ratio of √2 were first noted in 1786 by the German scientist and philosopher Georg Christoph Lichtenberg. The formats that became A2, A3, B3, B4 and B5 were developed in France on proposition of the mathematician Lazare Carnot and published for judiciary purpose in 1798 during the French Revolution. Early in the 20th century, Dr Walter Porstmann turned Lichtenberg's idea into a proper system of different paper sizes. Porstmann's system was introduced as a DIN standard (DIN 476) in Germany in 1922, replacing a vast variety of other paper formats. Even today, the paper sizes are called "DIN A4" (IPA: [diːn.ʔaː.fiːɐ̯]) in everyday use in Germany and Austria.

The DIN 476 standard spread quickly to other countries. Before the outbreak of World War II, it had been adopted by the following countries:

During World War II, the standard was adopted by Uruguay (1942), Argentina (1943) and Brazil (1943), and afterwards spread to other countries:

By 1975, so many countries were using the German system that it was established as an ISO standard, as well as the official United Nations document format. By 1977, A4 was the standard letter format in 88 of 148 countries. Today the standard has been adopted by all countries in the world except the United States and Canada. In Mexico, Costa Rica, Colombia, Venezuela, Chile, and the Philippines, the US letter format is still in common use, despite their official adoption of the ISO standard.

B series

In addition to the A series, there is a less common B series. The area of B series sheets is the geometric mean of successive A series sheets. So, B1 is between A0 and A1 in size, with an area of 0.707 m² ( ¹⁄_√2 m²). As a result, B0 is 1 metre wide, and other sizes in the B series are a half, a quarter or further fractions of a metre wide. While less common in office use, it is used for a variety of special situations. Many posters use B-series paper or a close approximation, such as 50 cm × 70 cm; B5 is a relatively common choice for books. The B series is also used for envelopes and passports. The B-series is widely used in the printing industry to describe both paper sizes and printing press sizes, including digital presses. B3 paper is used to print two US letter or A4 pages side by side using imposition; four pages would be printed on B2, eight on B1, etc.

C series

The C series is usually used for envelopes and is defined in ISO 269. The area of C series sheets is the geometric mean of the areas of the A and B series sheets of the same number; for instance, the area of a C4 sheet is the geometric mean of the areas of an A4 sheet and a B4 sheet. This means that C4 is slightly larger than A4, and slightly smaller than B4. The practical usage of this is that a letter written on A4 paper fits inside a C4 envelope, and C4 paper fits inside a B4 envelope.

Some envelope formats with mixed sides from adjacent sizes (and thus an approximate aspect ratio of 2:1) are also defined in national adaptations of the ISO standard, e.g. DIN C6/C5 is 114 mm × 229 mm where the common side to C5 and C6 is 162 mm.

Overview: ISO paper sizes

The tolerances specified in the standard are

German extensions

The German standard DIN 476 was published in 1922 and is the original specification of the A and B sizes. It differs in two details from its international successor:

DIN 476 provides for formats larger than A0, denoted by a prefix factor. In particular, it lists the formats 2A0 and 4A0, which are twice and four times the size of A0 respectively:

However, ISO 216:2007 notes 2A0 and 4A0 in the table of Main series of trimmed sizes (ISO A series) as well: "The rarely used sizes [2A0 and 4A0] which follow also belong to this series."

DIN 476 also specifies slightly tighter tolerances:

Swedish extensions

The Swedish standard SS 014711 generalized the ISO system of A, B, and C formats by adding D, E, F, and G formats to it. Its D format sits between a B format and the next larger A format (just like C sits between A and the next larger B). The remaining formats fit in between all these formats, such that the sequence of formats A4, E4, C4, G4, B4, F4, D4, H4, A3 is a geometric progression, in which the dimensions grow by a factor ¹⁶√2 from one size to the next. However, the SIS 014711 standard does not define any size between a D format and the next larger A format (called H in the previous example). Of these additional formats, G5 (169 × 239 mm) and E5 (155 × 220 mm) are popular in Sweden and the Netherlands for printing dissertations, but the other formats have not turned out to be particularly useful in practice and they have not been adopted internationally.

Japanese B-series variant

The JIS defines two main series of paper sizes. The JIS A-series is identical to the ISO A-series, but with slightly different tolerances. The area of B-series paper is 1.5 times that of the corresponding A-paper (instead of the factor √2 = 1.414... for the ISO B-series), so the length ratio is approximately 1.22 times the length of the corresponding A-series paper. The aspect ratio of the paper is the same as for A-series paper. Both A- and B-series paper is widely available in Japan, Taiwan and China, and most photocopiers are loaded with at least A4 and either one of A3, B4 and B5 paper.

There are also a number of traditional paper sizes, which are now used mostly by printers. The most common of these old series are the Shiroku-ban and the Kiku paper sizes.

Following Japanese paper sizes are included in Cascading Style Sheets (CSS): JIS-B4, JIS-B5.

Loose sizes

The United States, Canada and Mexico use a different system of paper sizes compared to the rest of the world. The current standard sizes are unique to that continent, although due to the size of the North American market and proliferation of both software and printing hardware from the region, other parts of the world have become increasingly familiar with these sizes (though not necessarily the paper itself). The traditional North American inch-based sizes differ from those described below.

Common loose sizes

Letter, Legal and Ledger/Tabloid are by far the most commonly used of these for everyday activities, and the only ones included in Cascading Style Sheets (CSS).

The origins of the exact dimensions of Letter size paper (8 ¹⁄₂ in × 11 in or 216 mm × 279 mm) are lost in tradition and not well documented. The American Forest and Paper Association argues that the dimension originates from the days of manual paper making, and that the 11-inch length of the page is about a quarter of "the average maximum stretch of an experienced vatman's arms." However, this does not explain the width or aspect ratio.

Outside of North America, Letter size may also be known as "American Quarto". If one accepts some trimming, the size is indeed one quarter of the old Imperial paper size known as Demy, 17 ¹⁄₂ in × 22 ¹⁄₂ in (444 mm × 572 mm).

Usage and adoption

US paper sizes are currently standard in the United States and at least in the Philippines, Colombia and Chile. The latter use US Letter, but their Legal size is 8 ¹⁄₂ in × 13 in (216 mm × 330 mm).

Mexico and Colombia have adopted the ISO standard, but US Letter format is still the system in use throughout the country. It is virtually impossible to encounter ISO standard papers in day-to-day uses, with "Carta 216 mm × 279 mm" (Letter), "Oficio 216 mm × 340 mm" (Government-Legal) and "Doble carta" (Ledger/Tabloid) being nearly universal. US sizes are also widespread and in common use in Colombia and some other countries in the Americas.

In Canada, US paper sizes are a de facto standard. The government, however, also uses ISO paper sizes.

Variant loose sizes

There is an additional paper size, 8 in × 10 ¹⁄₂ in (203 mm × 267 mm), to which the name Government-Letter was given by the IEEE Printer Working Group (PWG). It was prescribed by Herbert Hoover when he was Secretary of Commerce to be used for US government forms, apparently to enable discounts from the purchase of paper for schools, but more likely due to the standard use of trimming books (after binding) and paper from the standard letter size paper to produce consistency and allow "bleed" printing. In later years, as photocopy machines proliferated, citizens wanted to make photocopies of the forms, but the machines did not generally have this size paper in their bins. Ronald Reagan therefore had the US government switch to regular Letter size, which is both half an inch longer and wider. The former government size is still commonly used in spiral-bound notebooks, for children's writing and the like, a result of trimming from the current Letter dimensions.

By extension of the American standards, the halved Letter size, 5 ¹⁄₂ in × 8 in (140 mm × 203 mm), meets the needs of many applications. It is variably known as Statement, Stationery, Memo, Half Letter, Half A (from ANSI sizes) or simply Half Size. Like the similar-sized ISO A5, it is used for everything from personal letter writing to official aeronautical maps. Organizers, notepads, and diaries also often use this size of paper; thus 3-ring binders are also available in this size. Booklets of this size are created using word processing tools with landscape printing in two columns on letter paper which are then cut or folded into the final size.

In 1996, the American National Standards Institute adopted ANSI/ASME Y14.1 which defined a regular series of paper sizes based upon the de facto standard 8 ¹⁄₂ in × 11 in (216 mm × 279 mm) Letter size which it assigned "ANSI A", intended for technical drawings, hence sometimes labeled "Engineering". This series is somewhat similar to the ISO standard in that cutting a sheet in half would produce two sheets of the next smaller size and therefore also includes Ledger/Tabloid as "ANSI B". Unlike the ISO standard, however, the arbitrary base sides forces this series to have two alternating aspect ratios. For example, ANSI A is less elongated than A4, while ANSI B is more elongated than A3.

The Canadian standard CAN 2-9.60M "Paper Sizes for Correspondence" specifies P1 through P6 paper sizes, which are the ANSI paper sizes rounded to the nearest 5 mm.

With care, documents can be prepared so that the text and images fit on either ANSI or their equivalent ISO sheets at 1:1 reproduction scale.

Other, informal, larger sizes continuing the alphabetic series illustrated above exist, but they are not part of the series per se, because they do not exhibit the same aspect ratios. For example, Engineering F size is 28 in × 40 in or 711 mm × 1,016 mm with ca. 1.4286:1; it is commonly required for NAVFAC drawings, but is generally less commonly used. Engineering G size is 22 ¹⁄₂ in (572 mm) high, but it is a roll format with a variable width up to 90 in (2,286 mm) in increments of 8 ¹⁄₂ in (216 mm). Engineering H through N sizes are also roll formats.

Such huge sheets were at one time used for full-scale layouts of aircraft parts, automotive parts, wiring harnesses and the like, but are slowly being phased out, due to widespread use of computer-aided design (CAD) and computer-aided manufacturing (CAM). Some visual arts fields also continue to use these paper formats for large-scale printouts, such as for displaying digitally painted character renderings at life-size as references for makeup artists and costume designers, or to provide an immersive landscape reference.

Architectural sizes

In addition to the system as listed above, there is a corresponding series of paper sizes used for architectural purposes defined in the same standard, ANSI/ASME Y14.1, which is usually abbreviated "Arch". This series also shares the property that bisecting each size produces two of the size below, with alternating aspect ratios. It may be preferred by North American architects because the aspect ratios (4:3 and 3:2) are ratios of small integers, unlike their ANSI (or ISO) counterparts. Furthermore, the aspect ratio 4:3 matches the traditional aspect ratio for computer displays.

The size Arch E1 has a different aspect ratio because it derives from adding 6 inches to each side of Arch D or subtracting the same amount from Arch E. An intermediate size between Arch C and D with a long side of 30 inches (760 mm) does not exist.

Notebook sizes

The sizes listed above are for paper sold loose in reams. There are many sizes of tablets of paper, that is, sheets of paper bound at one edge, usually by a strip of plastic or hardened PVA adhesive. Often there is a pad of cardboard (also known as chipboard or greyboard) at the bottom of the stack. Such a tablet serves as a portable writing surface, and the sheets often have lines printed on them, usually in non-repro blue, to make writing in a line easier. An older means of binding is to have the sheets stapled to the cardboard along the top of the tablet; there is a line of perforated holes across every page just below the top edge from which any page may be torn off. Lastly, a pad of sheets each weakly stuck with adhesive to the sheet below, trademarked as "Post-It" or "Stick-Em" and available in various sizes, serve as a sort of tablet.

"Letter pads" are 8 ¹⁄₂ by 11 inches (215.9 by 279.4 mm), while the term "legal pad" is often used by laymen to refer to pads of various sizes including those of 8 ¹⁄₂ by 14 inches (215.9 by 355.6 mm). There are "steno pads" (used by stenographers) of 6 by 9 inches (152.4 by 228.6 mm).

In countries where the ISO sizes are standard, most notebooks and tablets are sized to ISO specifications (for example, most newsagents in Australia stock A4 and A3 tablets).

Office sizes

The international business card has the same size as the smallest rectangle containing a credit card. However, credit card size, as defined in ISO/IEC 7810, also specifies rounded corners and thickness.

Postage sizes

This implies that all postcards have a width:height aspect ratio in the range 1.18 to 1.71. The only ISO 216 size in the post card range is A6.

Grain

Most industry standards express the direction of the grain last when giving dimensions (that is, 17 × 11 inches is short grain paper and 11 × 17 inches is long grain paper), although alternatively the grain alignment can be explicitly indicated with an underline (11 × 17 is short grain) or the letter "M" for "machine" (11M × 17 is short grain). Grain is important because paper will crack if folded across the grain: for example, if a sheet 17 × 11 inches is to be folded to divide the sheet into two 8.5 × 11 halves, then the grain will be along the 11-inch side. Paper intended to be fed into a machine that will bend the paper around rollers, such as a printing press, photocopier or typewriter, should be fed grain side first so that the axis of the rollers is along the grain.

Traditional French paper sizes

Before the adoption of the ISO standard system in 1967, France had its own paper size system. Some of these formats are still used today, and they are standardized by the AFNOR. Their names come from the watermarks that the papers were branded with when they were handcrafted, which is still the case for certain art papers. They also generally exist in double versions where the smallest measure is multiplied by two, or in quadruple versions where both measures have been doubled.

Traditional British paper sizes

These sizes are no longer commonly used since the UK switched to ISO sizes. Many of these sizes were only used for making books (see bookbinding), and would never have been offered for ordinary stationery purposes.

Foolscap folio is often referred to simply as "folio" or "foolscap". Similarly, "quarto" is more correctly "copy draught quarto" and "Kings" is an alias for "Foolscap quarto".

Traditional inch-based paper sizes

Traditionally, a number of different sizes were defined for large sheets of paper, and paper sizes were defined by the sheet name and the number of times it had been folded. Thus a full sheet of "royal" paper was 25 × 20 inches, and "royal octavo" was this size folded three times, so as to make eight sheets, and was thus 10 ×  6 ¹⁄₄ inches.

Imperial sizes were used in the United Kingdom and its territories.

Demitab

The demitab or demi-tab (from the French "demi" or half tabloid) is 5 ¹⁄₂ in × 8 ¹⁄₂ in (140 mm × 216 mm), equal to one quarter of a sheet of 11 in × 17 in (279 mm × 432 mm) tabloid size paper. In actual circulation, the size 8 in × 10 ¹⁄₂ in (203 mm × 267 mm) is common for a demitab. Tabloid newspapers, which are "generally half the size of a broadsheet", also vary in size. To add to the lack of uniformity, broadsheets also vary in size.

PA4 or L4

A transitional size called PA4 (210 mm × 280 mm or 8.27 in × 11.02 in), sometimes dubbed L4, was proposed for inclusion into the ISO 216 standard in 1975. It has the height of Canadian P4 paper (215 mm × 280 mm, about  8 ¹⁄₂ in × 11 in) and the width of international A4 paper (210 mm × 297 mm or 8.27 in × 11.69 in), i.e. it uses the smaller value among the two for each side. The table below, shows how this format can be generalized into an entire format series.

The PA formats did not end up in ISO 216, because the committee decided that the set of standardized paper formats should be kept to the minimum necessary. However, PA4 remains of practical use today. In landscape orientation, it has the same 4:3 aspect ratio as the displays of traditional TV sets, some computer displays (e.g. iPad) and data projectors. PA4, with appropriate margins, is therefore a good choice as the format of presentation slides.

As a compromise between the two most popular paper sizes globally, PA4 is used today by many international magazines, because it can be printed easily on equipment designed for either A4 or US Letter. That means it is not as much a paper size than a page format.

F4

A non-standard F4 paper size is common in Southeast Asia. It is a transitional size with the shorter side from ISO A4 (210 mm) and the longer side from British Foolscap (13 in, 330 mm) and is sometimes known as (metric) foolscap or folio as well.

In Indonesia and Philippines, F4 paper is 215 mm x 330 mm (8.5 in x 13 in). In Indonesia it is sometimes called Folio, while in Philippines it is sometimes also called Long Bond.

A sheet of F4 can be cut from a sheet of SRA4 with very little wastage. The size is also smaller than its Swedish equivalent SIS F4 at 239 mm × 338 mm.

A0a

Although the movement is towards the international standard metric paper sizes, on the way there from the traditional ones there has been at least one new size just a little larger than that used internationally.

British architects and industrial designers once used a size called "Antiquarian", 31 in × 53 in (787 mm × 1,346 mm), as listed above, but given in the New Metric Handbook (Tutt & Adler 1981) as 813 mm × 1,372 mm (32 in × 54 in) for board size. This is a little larger than ISO A0, 841 mm × 1189 mm. So for a short time, a size called A0a of 1,000 mm × 1,370 mm (39.4 in × 53.9 in) was used in Britain, which is actually just a slightly shorter version of ISO B0 at 1414 mm.

Pliego

The most common paper sizes used for commercial and industrial printing in Colombia are based upon a size referred to as pliego that is ISO B1 (707 mm × 1000 mm) cut to full decimetres. Smaller sizes are derived by halving as usual and just get a vulgar fraction prefix:  ¹⁄₂ pliego and  ¹⁄₄ pliego.

Newspaper sizes

Newspapers have a separate set of sizes.

In a recent trend many newspapers have been undergoing what is known as "web cut down", in which the publication is redesigned to print using a narrower (and less expensive) roll of paper. In extreme examples, some broadsheet papers are nearly as narrow as traditional tabloids.