Grammage

 ( Paper ) 

Grammage and basis weight, in the pulp and paper industry, are the area density of a paper product, that is, its mass per unit of area. Two ways of expressing the area density of a paper product are commonly used:

• Expressed in (g) per square metre (g/m²), regardless of its thickness (caliper)International Standard ISO 536: Paper and board – Determination of grammage. International Organization for Standardization, Geneva. (known as grammage). This is the measure used in most parts of the world. It is often notated as gsm on paper product labels and spec sheets.
• Expressed in terms of the mass per number of sheets of a specific paper size (known as basis weight). The convention used in the United States and a few other countries using US-standard paper sizes is pounds (lb) per paper ream of 500 (or in some cases 1000) sheets of a given (raw, still uncut) basis size. The traditional British practice is pounds per ream of 480, 500, 504, or 516 sheets of a given basis size. Japanese paper is expressed as the weight in (kg) per 1,000 sheets.

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Grammage In the metric system, the mass per unit area of all types of paper and paperboard is expressed in terms of grams per square metre (g/m²). This quantity is commonly called in both English language and French language, though printers in most English-speaking countries still refer to the "weight" of paper.

$\backslash text\{Grammage\}\; =\; \backslash frac\{\backslash text\{mass\}\; \backslash text\{\; (g)\}\}\{\backslash text\{length\}\; \backslash text\{\; \}(\backslash text\{m\})\; \backslash times\; \backslash text\{width\}\; \backslash text\{\; \}\; (\backslash text\{m\})\}$

Typical office paper has , therefore a typical A4 sheet ( of a square metre) weighs . The abbreviation "gsm" instead of the standard g/m² symbol is also widely encountered in English-speaking countries.

Typically grammage is measured in paper mill on-line by a quality control system and verified by laboratory measurement.

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Basis weight Basis weight of paper is the density of paper expressed in terms of the mass (in pound) of a paper ream of paper of given dimensions and a sheet count. The American and the traditional British systems are largely the same, with only minor differences: the paper dimensions and the sheet count are different.

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United States In the US system, the weight is specified in avoirdupois pounds and the sheet count of a paper ream is usually 500 sheets. However, the mass specified is not the mass of the ream that is sold to the customer. Instead, it is the mass of the uncut "basis ream" in which the sheets have some larger size (parent size). Often, that is a size used during the manufacturing process before the paper is cut to the dimensions in which it is sold. So, to compute the mass per area, one must know

• the mass of the basis ream,
• the number of sheets in that ream, and
• the dimensions of an "uncut" sheet in that ream.

The standard dimensions and sheet count of a ream vary according to the type of paper. These "uncut" basis sizes are not normally labelled on the product, are not formally standardized, and therefore have to be guessed or inferred somehow from trading practice. Historically, this convention is the product of pragmatic considerations such as the size of a sheet mold.

By using the same basis sheet size for the same type of paper, consumers can easily compare papers of differing brands. Twenty-pound bond paper is always lighter and thinner than 32-pound bond, no matter what its cut size, and 20-pound bond letter size and 20-pound bond legal size papers are the same weight paper with a different cut size.

However, a sheet of common copy paper that has a basis weight of does not have the same mass as the same size sheet of coarse paper (newsprint). In the former case, the standard ream is 500 sheets of paper, and in the latter, 500 sheets of paper. Here are some basic ream sizes for various types of paper. Units are inches except where noted.

>

500
500
500
500
500 or 1000
500
500
480
500
500
500
500
1000 ( per ream)

Sheets can be cut into four sheets, a standard for business stationery known conventionally as letter sized paper. So, the ream became commonly used. The book-paper ream developed because such a size can easily be cut into sixteen book sized sheets without significant waste (nominally before trimming and binding).

Early newsprint presses printed sheets in size, and so the ream dimensions for newsprint became , with 500 sheets to a ream. Newsprint was made from ground wood pulp, and ground wood hanging paper (wallpaper) was made on newsprint machines. Newsprint was used as wrapping paper, and the first paper bags were made from newsprint. The newsprint ream standard also became the standard for packaging papers, even though in packaging papers kraft process pulp, rather than ground wood, was used for greater strength.

Paper weight is sometimes stated using the "#" symbol. For example, "20#" means "20 pounds per basis ream of that kind of paper". When the density of a ream of paper is given in pounds, it is often accompanied by its "M weight" (M is 1000 in Roman numerals). The M weight is the weight (in pounds) of 1000 cut sheets. Paper suppliers will often charge by M weight, since it is always consistent within a specific paper size, and because it allows a simple weight calculation for shipping charges.

For example, a 500-sheet ream of 20# copy paper may be specified "10 M". 1000 cut sheets (or two reams) will weigh , half of the four reams of cut paper resulting from the 20# basis ream of paper.

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United Kingdom

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Overview of the traditional British system

Like the American system, the traditional British system also involves the use of basis weight to express the area density of paper (and, indirectly, paper thickness) in the course of buying and selling paper. The British paper industry exclusively used basis weight before 1968.Page 11, January, 1968 edition, Highlight

In the traditional British system, basis weight is also expressed in terms of the weight of an imaginary ream of paper of a certain size. The underlying concept is that a ream of paper of the stated paper size and of the same thickness as the paper the parties are dealing with would have the stated weight. The weight is expressed in pound. As to paper sizes (basis sizes), they can, theoretically, be any sizes, but, by custom, a number of common sizes emerged. In the 1960s, even the metric A1Page 3, July, 1967 edition, Highlight and A2Page 3, October, 1967 edition, Highlight had been used as basis sizes alongside the British ones.

The following are commonPages , , and , Paper and Its Uses (1919 edition)Pages , , and , Paper and Its Uses (1939 edition), The Papermakers' Pocket Book (1911) British basis sizes (sizes of British uncut paper):

+Common British basis sizes	Note 1: The Italicised writing‑paper and printing‑paper sizes were in use only prior to the 1925 standardisation, Paper and Its Uses (1939 edition) of writing‑paper and printing‑paper sizes. The 1925 standardisation did not apply to wrapping‑paper sizes. Note 2: The underlined writing‑paper and printing‑paper sizes were in use after the 1925 standardisation but were not adopted as standard sizes, Paper and Its Uses (1939 edition) by British Standards Institution specification number 730 of 1937. Note 3: The wrapping‑paper sizes marked with '*' were not adopted as standard sizes by British Standards Institution specification number 730 of 1937.
Atlas	26 in × 34 in
Copy	16 in × 20 in
Double elephant (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	27 in × 40 in
Double imperial	30 in × 44 in
Double large post	21 in × 33 in
Double post (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	19 in × 30 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 19 in × 30 in)
Double pott	15 in × 25 in
Double small demy (known as 'double demy' before the 1925 standardisation)	20 in × 31 in
Double small foolscap (known as 'double foolscap' before British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	16 in × 26 in
Double small royal (known as 'double royal' before the 1925 standardisation)	24 in × 38 in
Elephant	23 in × 28 in
Imperial	22 in × 30 in
Large post	16 in × 21 in
Pinched post	14 in × 18 in
Post (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	15 in × 19 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 15 in ×19 in)
Pott	12 in × 15 in
Sheet‑and‑a‑half small foolscap (known as 'sheet‑and‑a‑half foolscap' before British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	13 in × 24 in (before the 1925 standardisation, 13 in × 24 in)
Sheet‑and‑a‑third small foolscap (introduced by the 1925 standardisation) (known as 'sheet‑and‑a‑third foolscap' before British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	13 in × 22 in
Small demy (known as 'demy' before the 1925 standardisation)	15 in × 20 in
Small foolscap (known as 'foolscap' before British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	13 in × 16 in
Small medium (known as 'medium' before the 1925 standardisation)	17 in × 22 in
Small post (introduced by the 1925 standardisation)	14 in × 18 in
Small royal (known as 'royal' before the 1925 standardisation)	19 in × 24 in
Super royal	19 in × 27 in (before the 1925 standardisation, 19 in × 27 in)
Copy	16 in × 20 in
Crown	15 in × 20 in
Demy	17 in × 22 in
Double crown	20 in × 30 in
Double demy	22 in × 35 in
Double elephant (also known as 'double large royal') (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	27 in × 40 in
Double globe	28 in × 38 in
Double imperial	30 in × 44 in
Double foolscap (known as 'double large foolscap' after the 1925 standardisation and before being re‑named by British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	17 in × 27 in
Double large post	21 in × 33 in
Double medium	23 in × 36 in
Double post (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	19 in × 30 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 19 in × 31 in)
Double pott	15 in × 25 in
Double royal	25 in × 40 in
Elephant	23 in × 28 in
Foolscap (known as 'large foolscap' after the 1925 standardisation and before being re‑named by British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	13 in × 17 in
Imperial	22 in × 30 in
Large post	16 in × 21 in
Large royal (introduced by the 1925 standardisation)	20 in × 27 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 20 in × 27 in)
Medium	18 in × 23 in
Music demy	14 in × 20 in
Post (adopted by British Standards Institution specification number 730 of 1937 but not the 1925 standardisation)	15 in × 19 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 15 in × 19 in)
Pott	12 in × 15 in
Quad crown	30 in × 40 in
Quad demy	35 in × 45 in
Quad foolscap (known as 'quad large foolscap' after the 1925 standardisation and before being re‑named by British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	27 in × 34 in
Quad globe	38 in × 56 in
Quad pott	25 in × 30 in
Quad royal	40 in × 50 in
Royal	20 in × 25 in
Super royal	20 in × 27 in
Bag cap	20 in × 24 in (prior to re‑definition by British Standards Institution specification number 730 of 1937, 19 in × 24 in)
Casing	36 in × 46 in (across the island of Ireland, 36 in × 48 in)
Double bag cap*	24 in × 39 in*
Double crown	20 in × 30 in
Double double imperial	45 in × 58 in
Double elephant*	31 in × 46 in*
Double imperial	29 in × 45 in
Double medium	23 in × 36 in
Double small cap*	25 in × 34 in*
Double small hand*	20 in × 29 in*
Elephant*	24 in × 32 in*
Extra large casing	40 in × 48 in
Haven cap* (sometimes called 'havon cap')	21 in × 26 in*
Imperial	22 in × 29 in
Kent cap*	18 in × 21 in*
Lumber hand*	17 in × 22 in*
Quad crown	30 in × 40 in
Quad foolscap* (known as 'quad large foolscap' after the 1925 standardisation and before British Standards Institution specification number 730 of 1937) ('foolscap' is sometimes shortened to 'cap' or 'cap')	27 in × 34 in*
Quad royal*	40 in × 50 in*
Quad small hand*	30 in × 40 in*
Royal*	20 in × 25 in*
Saddleback	36 in × 45 in
Small cap*	17 in × 25 in*
Small hand*	15 in × 20 in*
(No name)	20 in × 24 in*
(No name)	20 in × 28 in*
(No name)	21 in × 31 in*
(No name)	21 in × 34 in*
(No name)	22 in × 32 in*
(No name)	22 in × 35 in*
(No name)	23 in × 34 in*
(No name)	24 in × 30 in*
(No name)	24 in × 36 in*
(No name)	24 in × 40 in*
(No name)	26 in × 36 in*
(No name)	28 in × 45 in*
(No name)	29 in × 44 in*
(No name)	30 in × 38 in*
(No name)	30 in × 46 in*
(No name)	34 in × 36 in*
(No name)	36 in × 36 in*
(No name)	36 in × 48 in*
(No name)	38 in × 48 in*
(No name)	45 in × 56 in*

One ream in the context of basis weight (basis ream) can be 480 sheets, 500 sheets, 504 sheets, or 516 sheets: there is no fixed rule on when a certain definition was applied; however, starting from the 1950s, the trend of moving towards 500 sheets emerged.

Basis weight is commonly expressed in terms of pound per ream of paper of a certain size, in the format of 'numberlb paper' (e. g., '21lb large post' ('21 pounds per ream of large post paper')). Since there are basis reams of different sizes, unless the context leaves no room for ambiguity, the number of sheets in the basis ream is also given after the paper size to avoid misunderstanding: in such case, basis weight is expressed in the format of 'numberlb paper number', such as '21lb large post 480' ('21 pounds per 480‑sheet ream of large post paper'). In the United Kingdom, '#' has never been used to express paper weight because it is called 'hash', instead of 'pound', in British English.

Demy traditionally plays the role of the default basis size for expressing basis weights: in the British paper industry, there was a device, called 'demy scale', that was used to measure the weights of different paper samples in pound per ream of demy paper (480‑sheet, 500‑sheet, and 516‑sheet reams)., Paper and Its Uses (1919 edition)

Below is a list of commonBased on the basis weights mentioned in the paper‑related advertisements and articles in the following newspapers and paper‑industry magazines published during the days when the British paper industry exclusively used basis weights:

• Advertisement by J. Moore, page 5, 15th December, 1853 edition, The Sydney Morning Herald
• 'London School Board', page 69, March, 1887 edition, The Stationery Trade Review
• Pages 24, 34, and 87, 25th January, 1892 edition, The Printing World
• Advertisement immediately after page 40, March–April, 1892 edition, The British Printer
• Supplement immediately after page 106 and page 122, 5th March, 1892 edition, The Printing World
• Advertisements between pages 208 and 209 and on page 222, 25th May, 1892 edition, The Printing World
• Page 362, 25th August, 1892 edition, The Printing World
• Page 461, 25th October, 1892 edition, The Printing World
• Respective advertisements from John Muir and Strong & Hanbury on two unnumbered pages of the advertisement supplement immediately after page 452, the red-inked page 37 after page 452, and the advertisement from Alexander Cowan & Sons on a red-inked page 12 of a certain advertisement supplement after page 452, November–December, 1893 edition, The British Printer
• Page 20 of the advertisement supplement, January–February, 1897 edition, The British Printer
• Pages 29–32, March, 1906 edition, Tanner's Trade Circular
• Pages 50–52 and the back of the back cover, April, 1906 edition, Tanner's Trade Circular
• Pages 57, 59, 67, and 68, May, 1906 edition, Tanner's Trade Circular
• Page 70, June, 1906 edition, Tanner's Trade Circular
• Pages 114, 115, 122, 131, and 132, July, 1906 edition, Tanner's Trade Circular
• Pages 147 and 148, August, 1906 edition, Tanner's Trade Circular
• Back of the back cover, September, 1906 edition, Tanner's Trade Circular
• Back of the back cover, October, 1906 edition, Tanner's Trade Circular
• Page 183 and the back of the back cover, November, 1906 edition, Tanner's Trade Circular
• Back of the back cover and pages 202 and 219, December, 1906 edition, Tanner's Trade Circular
• Pages 14 and 22 and the back of the back cover, February, 1907 edition, Tanner's Trade Circular
• Back of the cover; pages 26, 27, 38, and 44–47; and the back of the back cover, March, 1907 edition, Tanner's Trade Circular
• Back of the cover and pages 51 and 60–70, April, 1907 edition, Tanner's Trade Circular
• Pages 75, 77, 82, 93, and 94, May, 1907 edition, Tanner's Trade Circular
• Back of the cover and pages 147, 149, 158, and 165–167, August, 1907 edition, Tanner's Trade Circular
• Pages 229, 238, and 239, November, 1907 edition, Tanner's Trade Circular
• Back of the cover and the back of the back cover, December, 1907 edition, Tanner's Trade Circular
• Back cover, July, 1908 edition, Tanner's Trade Circular
• Back of the back cover and pages 3, 5, 12, and 14, January, 1910 edition, Tanner's Trade Circular
• Back of the cover; pages 45, 47, and 54; and the back of the back cover, March, 1910 edition, Tanner's Trade Circular
• Pages 43, 52, and 62, April, 1910 edition, Tanner's Trade Circular
• Back of the cover; pages 123, 125, 128, 132, and 138; and the back cover, July, 1910 edition, Tanner's Trade Circular
• Pages 148, 154, and 155, August, 1910 edition, Tanner's Trade Circular
• Pages 163, 168, 174, and 175, September, 1910 edition, Tanner's Trade Circular
• Pages 181 and 188, October, 1910 edition, Tanner's Trade Circular
• Pages 214 and 218, November, 1910 edition, Tanner's Trade Circular
• Pages 4 and 6 and the back of the back cover, January, 1911 edition, Tanner's Trade Circular
• Pages 36 and 37, February, 1911 edition, Tanner's Trade Circular
• Pages 43, 52, 56, and 57, March, 1911 edition, Tanner's Trade Circular
• Page 69, April, 1911 edition, Tanner's Trade Circular
• Pages 82 and 96, May, 1911 edition, Tanner's Trade Circular
• Page 146, August, 1911 edition, Tanner's Trade Circular
• Page 172, September, 1911 edition, Tanner's Trade Circular
• Pages 194 and 195 and the back cover, October, 1911 edition, Tanner's Trade Circular
• Pages 205, 206, and 226, November, 1911 edition, Tanner's Trade Circular
• Pages 238 and 239, December, 1911 edition, Tanner's Trade Circular
• Page 28, February, 1912 edition, Tanner's Trade Circular
• Pages 46, 48, 58, and 60, March, 1912 edition, Tanner's Trade Circular
• Page 82, April, 1912 edition, Tanner's Trade Circular
• Back of the back cover and page 86, May, 1912 edition, Tanner's Trade Circular
• Pages 114 and 118, June, 1912 edition, Tanner's Trade Circular
• Page 121, July, 1912 edition, Tanner's Trade Circular
• Page 182, October, 1912 edition, Tanner's Trade Circular
• Page 26, February, 1913 edition, Tanner's Trade Circular
• Page 35, March, 1913 edition, Tanner's Trade Circular
• Pages 74 and 75, May, 1913 edition, Tanner's Trade Circular
• Pages 116 and 122 and the back cover, August, 1913 edition, Tanner's Trade Circular
• Pages 147, 148, and 154, October, 1913 edition, Tanner's Trade Circular
• Page 179, December, 1913 edition, Tanner's Trade Circular
• Page 37, March, 1914 edition, Tanner's Trade Circular
• Page 58 and the back of the back cover, April, 1914 edition, Tanner's Trade Circular
• Pages 77–79, May, 1914 edition, Tanner's Trade Circular
• Pages 26, 82, 92, and 98 and the back of the back cover, June, 1914 edition, Tanner's Trade Circular
• Page 100, July, 1914 edition, Tanner's Trade Circular
• Page 114, August, 1914 edition, Tanner's Trade Circular
• Pages 146 and 152, December, 1914 edition, Tanner's Trade Circular
• Pages 8, 12, and 14, January, 1922 edition, Tanner's Trade Circular
• Pages 18, 26, and 30, February, 1922 edition, Tanner's Trade Circular
• Pages 34, 38, and 40 and the back of the back cover, March, 1922 edition, Tanner's Trade Circular
• Pages 50, 51, and 114, April, 1922 edition, Tanner's Trade Circular
• Pages 115 and 126, August, 1922 edition, Tanner's Trade Circular
• Pages 146, 147, and 149, October, 1922 edition, Tanner's Trade Circular
• Page 178 and the back of the back cover, December, 1922 edition, Tanner's Trade Circular
• Pages 70, 74, and 76, May, 1923 edition, Tanner's Trade Circular
• Pages 120, 121, and 124, August, 1923 edition, Tanner's Trade Circular
• Page 138, September, 1923 edition, Tanner's Trade Circular
• Pages 152 and 154 and the back cover, October, 1923 edition, Tanner's Trade Circular
• Back of the cover and pages 178, 184, 185, and 188, December, 1923 edition, Tanner's Trade Circular
• Back of the cover and pages 4, 8, 9, and 12, January, 1924 edition, Tanner's Trade Circular
• Back of the back cover, April, 1952 edition, Highlight
• Pages 49 and 52, April, 1953 edition, Highlight
• Back of the back cover, July, 1953 edition, Highlight
• Page 75, October, 1953 edition, Highlight
• Back of the back cover, January, 1954 edition, Highlight
• Page 4, April, 1954 edition, Highlight
• Back of the cover and page 17, July, 1954 edition, Highlight
• Page 33, October, 1954 edition, Highlight
• Back of the cover, January, 1955 edition, Highlight
• Page 11, April, 1955 edition, Highlight
• Back of the back cover, July, 1955 edition, Highlight
• Back of the cover and page 33, October, 1955 edition, Highlight
• Back of the back cover, January, 1956 edition, Highlight
• Page 11 and the back of the back cover, April, 1956 edition, Highlight
• Back of the cover and the back of the back cover, July, 1956 edition, Highlight
• Page 28, October, 1956 edition, Highlight
• Back of the back cover, January, 1957 edition, Highlight
• Back of the cover and page 3, April, 1957 edition, Highlight
• Back of the back cover, October, 1958 edition, Highlight
• Page 11, January, 1959 edition, Highlight
• Back of the cover, October, 1959 edition, Highlight
• Page 10, January, 1960 edition, Highlight
• Pages 15, 17, and 23 and the back of the back cover, April, 1960 edition, Highlight
• Back of the cover, July, 1960 edition, Highlight
• Page 45 and the back of the back cover, October, 1960 edition, Highlight
• Page 3 and the back of the back cover, July, 1961 edition, Highlight
• Back of the cover and page 11, January, 1962 edition, Highlight
• Page 3, April, 1962 edition, Highlight
• Page 11 and the back of the back cover, April, 1963 edition, Highlight
• Page 11 and the back of the back cover, October, 1963 edition, Highlight
• Back of the back cover, July, 1964 edition, Highlight
• Page 11, July, 1965 edition, Highlight
• Back of the cover and the back of the back cover, January, 1966 edition, Highlight
• Back of the cover, January, 1967 edition, Highlight
• Page 3, July, 1967 edition, Highlight
• Page 3, October, 1967 edition, Highlight basis weights of paper stocked by British paper merchants:

+Common British basis weights and their metric and American equivalents ! colspan="5"	Writing paper
Common British basis weights (various paper sizes and ream sizes)	Equivalent weight of a 500‑sheet ream of large post paper, a British uncut writing paper commonly used to express the basis weight of writing paper (rounded to the nearest quarter) (a common British basis for intra‑category comparison)	Equivalent weight of a 500‑sheet ream of demy paper, a British uncut printing paper commonly used by default to express the basis weight of different types of paper (rounded to the nearest quarter) (a common British basis for cross‑category comparison)	Equivalent grammage (rounded to the nearest one)	Equivalent weight of a 500‑sheet ream of bond paper, an American uncut paper commonly used to express the basis weight of paper (rounded to the nearest quarter) (a common American basis for cross‑category comparison)
11	11	13	46	12
11	11	12	45	11
12	12	13	49	13
14	14	16	59	15
15	15	17	63	16
15	15	17	61	16
15	15	17	60	16
17	17	20	72	19
18	18	21	76	20
18	18	20	73	19
18	17	20	72	19
19	19	22	80	21
20	20	23	85	22
21	22	24	89	23
21	21	23	85	22
21	20	23	85	22
22	23	26	93	24
22	21	24	89	23
23	24	27	97	25
23	23	26	93	24
23	22	26	93	24
24	25	28	101	27
24	23	27	97	25
25	26	29	106	28
25	25	28	101	27
26	27	30	110	29
26	25	29	105	27
27	28	32	114	30
27	26	30	109	29
28	29	33	118	31
28	27	31	113	30
30	31	35	127	33
22	11	12	45	11
30	15	17	63	16
30	15	17	61	16
30	15	17	60	16
36	18	21	76	20
36	18	20	73	19
36	17	20	72	19
42	22	24	89	23
42	21	23	85	22
42	20	23	85	22
44	21	24	89	23
13	12	13	49	13
18	17	19	68	18
21	18	21	76	20
21	19	22	79	21
23	21	24	88	23
23	20	23	83	22
24	21	24	87	23
25	23	26	95	25
25	22	25	91	24
30	26	29	106	28
34	32	36	129	34
40	35	40	145	38
13	11	12	44	11
14	12	13	51	13
18	15	17	64	17
18	15	17	61	16
21	17	20	71	19
21	18	20	73	19
25	21	23	85	22
28	23	26	95	25
26	11	12	44	11
36	15	17	61	16
46	20	22	81	21
46	19	21	77	20
48	20	22	81	21
50	20	23	84	22
60	26	29	106	28
60	25	28	102	27
70	29	33	119	31
20	15	18	64	17
24	19	22	80	21
24	19	21	77	20
25	20	23	84	22
26	20	23	83	22
28	23	26	94	25
28	22	25	90	24
28	22	25	89	23
30	24	28	100	26
30	23	26	96	25
32	25	28	102	27
34	26	30	108	28
36	29	33	121	32
14	11	13	46	12
14	11	12	44	11
20	15	17	64	17
20	15	17	61	16
24	19	21	77	20
24	18	20	74	19
28	21	24	86	22
30	17	19	70	18
32	19	22	78	20
32	18	20	74	19
36	20	23	84	22
40	23	26	94	25
40	23	26	93	24
44	25	29	103	27
46	27	31	112	29
50	28	32	117	31
60	34	39	139	37
88	25	29	103	27
100	28	32	117	31
25	29	33	118	31
38	44	50	180	47
18	29	33	121	32
48	18	20	73	19
50	19	22	80	21
72	39	44	160	42
18	22	25	91	24
20	25	28	101	27
22	27	31	111	29
72	17	20	72	19
84	22	24	89	23
29	38	43	156	41
44	34	39	141	37
54	37	42	152	40
Common British basis weights (various paper sizes and ream sizes)	Equivalent weight of a 500‑sheet ream of double crown paper, a British uncut printing paper commonly used to express the basis weight of printing paper (rounded to the nearest quarter) (a common British basis for intra‑category comparison)	Equivalent weight of a 500‑sheet ream of demy paper, a British uncut printing paper commonly used by default to express the basis weight of different types of paper (rounded to the nearest quarter) (a common British basis for cross‑category comparison)	Equivalent grammage (rounded to the nearest one)	Equivalent weight of a 500‑sheet ream of bond paper, an American uncut paper commonly used to express the basis weight of paper (rounded to the nearest quarter) (a common American basis for cross‑category comparison)
17	17	11	42	11
19	19	13	46	12
20	20	13	49	13
20	19	12	45	12
21	22	14	51	13
22	23	15	54	14
23	24	15	56	15
23	22	15	53	14
24	23	15	56	14
24	23	15	55	14
25	26	17	61	16
25	24	16	58	15
26	27	17	63	16
26	25	17	60	16
26	25	16	59	15
27	28	18	66	17
27	27	17	63	16
27	26	17	63	16
28	29	19	68	18
28	27	17	64	17
29	30	19	71	18
30	31	20	73	19
30	30	19	70	18
30	29	19	70	18
30	29	19	68	18
31	30	20	72	19
32	33	22	78	20
32	31	20	74	19
32	31	20	73	19
33	35	22	81	21
33	32	21	77	20
34	33	22	79	21
34	33	21	77	20
35	36	24	85	22
36	37	24	88	23
36	36	23	84	22
36	35	23	84	22
36	35	23	82	21
38	39	26	93	24
38	37	24	88	23
38	36	24	86	23
39	38	25	91	24
40	41	27	98	26
40	40	26	94	25
40	39	26	93	24
40	38	25	91	24
42	43	28	103	27
42	41	27	98	26
44	45	30	107	28
44	44	28	103	27
44	42	28	100	26
45	47	30	110	29
45	45	29	105	28
46	48	31	112	29
46	45	30	107	28
46	44	29	104	27
47	49	32	115	30
50	52	34	122	32
50	50	32	117	31
50	49	32	116	31
50	48	31	114	30
52	54	35	127	33
54	56	37	132	35
54	52	34	123	32
55	57	37	134	35
56	54	35	127	33
57	59	39	139	37
58	58	38	136	36
60	62	41	146	39
60	60	39	141	37
60	59	39	139	37
60	58	38	136	36
61	63	41	149	39
76	79	52	186	49
79	76	50	179	47
80	83	54	195	52
80	79	52	186	49
40	19	12	45	12
48	23	15	56	14
50	26	17	61	16
54	27	17	63	16
60	31	20	73	19
60	30	19	70	18
60	29	19	70	18
60	29	19	68	18
64	31	20	73	19
68	33	21	77	20
70	36	24	85	22
70	34	22	79	21
72	36	23	84	22
72	35	23	84	22
80	40	26	94	25
80	39	26	93	24
80	38	25	91	24
86	44	29	105	28
88	44	29	103	27
96	46	30	109	29
100	50	32	117	31
100	49	32	116	31
100	48	31	114	30
120	60	39	141	37
120	59	39	139	37
120	58	38	136	36
14	22	14	52	13
16	25	16	60	15
17	27	17	63	16
18	28	18	67	17
18	27	17	64	17
19	30	19	71	18
20	31	20	74	19
20	30	19	71	18
20	29	19	69	18
21	33	22	78	20
24	36	23	85	22
25	39	26	93	24
26	41	27	97	25
28	44	29	104	27
29	46	30	108	28
30	47	31	112	29
30	44	29	104	27
32	50	33	119	31
34	54	35	126	33
35	55	36	130	34
36	57	37	134	35
44	69	45	164	43
64	94	62	221	59
23	18	12	43	11
25	19	13	46	12
26	20	13	48	12
28	22	14	52	13
28	20	13	48	13
30	23	15	56	14
30	22	14	52	13
32	25	16	60	15
32	24	15	57	15
32	23	15	55	14
33	26	17	61	16
34	27	17	63	16
34	25	16	60	16
34	25	16	59	15
35	27	18	65	17
36	28	18	67	17
36	27	18	64	17
36	27	17	64	17
36	26	17	62	16
38	30	19	71	18
38	28	18	67	18
40	31	20	74	19
40	30	20	71	19
40	30	19	71	18
40	29	19	69	18
42	33	22	78	20
42	31	20	73	19
44	32	21	76	20
45	34	22	80	21
45	33	21	78	20
46	36	24	86	22
46	34	22	80	21
47	34	22	81	21
48	38	25	89	23
48	36	24	86	22
48	36	23	85	22
48	35	23	83	22
50	39	26	93	24
52	39	25	92	24
53	39	25	92	24
54	42	28	100	26
55	43	28	102	27
55	40	26	95	25
56	44	29	104	27
56	41	27	97	25
60	47	31	112	29
60	45	29	106	28
60	44	29	104	27
64	47	31	111	29
68	54	35	126	33
69	54	36	128	34
70	55	36	130	34
72	53	35	125	33
74	58	38	138	36
80	60	39	142	37
88	65	42	152	40
89	70	46	166	44
19	28	18	67	18
20	30	19	71	18
24	36	23	85	22
25	37	24	88	23
25	36	23	84	22
27	40	26	96	25
28	42	27	99	26
29	43	28	103	27
30	45	29	106	28
30	42	27	99	26
31	46	30	110	29
32	48	31	113	30
33	46	30	109	29
34	51	33	120	32
34	49	32	115	30
35	52	34	124	33
38	53	35	125	33
40	60	39	142	37
40	57	37	135	35
40	56	36	132	35
45	68	44	159	42
48	72	47	170	45
50	72	47	168	44
53	76	50	179	47
55	83	54	195	51
42	31	20	74	19
50	37	24	88	23
50	36	23	84	22
50	35	23	82	22
55	39	26	93	24
60	43	28	102	27
60	42	27	99	26
62	45	29	105	28
64	45	29	105	28
65	47	31	110	29
68	51	33	120	32
68	49	32	115	30
69	50	32	117	31
70	50	33	119	31
80	58	38	136	36
80	56	36	132	35
20	25	16	59	15
21	24	16	57	15
22	27	18	64	17
23	28	18	67	18
24	30	19	70	18
24	28	18	67	17
24	28	18	65	17
25	29	19	68	18
26	32	21	76	20
26	30	19	71	18
27	31	20	74	19
30	37	24	88	23
30	35	23	82	21
31	38	25	91	24
32	40	26	94	25
33	41	27	97	25
34	42	28	100	26
36	45	29	105	28
36	41	27	98	26
37	46	30	108	28
38	47	31	111	29
39	48	32	114	30
40	50	32	117	31
40	47	31	112	29
40	46	30	109	29
41	51	33	120	32
42	52	34	123	32
44	55	36	129	34
45	56	37	132	35
47	58	38	138	36
50	62	41	146	39
50	59	39	139	37
50	58	38	136	36
51	63	41	149	39
60	75	49	176	46
61	76	50	179	47
66	82	54	193	51
67	79	52	187	49
70	87	57	205	54
32	19	12	45	12
37	23	15	54	14
40	23	15	56	14
42	24	16	57	15
46	28	18	67	18
48	28	18	67	17
48	28	18	65	17
50	30	19	70	18
50	29	19	68	18
54	31	20	74	19
60	36	23	84	22
60	35	23	84	22
60	35	23	82	21
66	40	26	94	24
72	42	28	100	26
72	41	27	98	26
75	45	29	105	28
80	47	31	112	29
80	46	30	109	29
91	53	34	124	33
100	59	39	139	37
100	58	38	136	36
160	47	31	112	29
16	33	22	78	20
20	41	27	98	26
27	56	37	132	35
16	21	14	51	13
21	28	18	67	17
22	30	19	70	18
23	29	19	68	18
24	32	21	77	20
25	31	20	74	19
26	35	23	83	22
28	38	25	89	23
28	35	23	83	22
29	39	26	93	24
30	40	26	96	25
30	38	25	89	23
32	43	28	102	27
36	49	32	115	30
36	45	30	107	28
38	51	34	121	32
40	54	35	128	34
45	61	40	144	38
54	73	48	172	45
67	91	59	214	56
46	29	19	68	18
48	31	20	73	19
49	31	20	73	19
50	31	20	74	19
56	36	23	85	22
56	35	23	83	22
60	39	25	91	24
60	38	25	89	23
68	46	30	108	28
64	23	15	55	14
80	29	19	69	18
84	31	20	73	19
96	36	23	85	22
120	45	29	106	28
120	44	29	104	27
30	26	17	62	16
36	31	20	74	19
40	35	23	83	22
46	43	28	102	27
50	44	29	103	27
56	53	34	124	33
60	52	34	124	33
70	66	43	155	41
120	105	69	248	65
13	27	18	64	17
14	29	19	69	18
22	46	30	108	28
23	48	31	113	30
24	50	33	118	31
16	28	19	68	18
17	30	20	72	19
18	32	21	76	20
18	31	20	73	19
21	38	24	89	23
21	36	23	85	22
21	36	23	85	22
24	43	28	101	27
25	45	29	106	28
26	47	30	110	29
27	48	32	114	30
28	50	33	118	31
29	52	34	123	32
30	54	35	127	33
30	51	33	121	32
31	56	36	131	34
32	57	38	135	36
34	61	40	144	38
36	65	42	152	40
44	79	52	186	49
36	30	19	71	18
60	54	35	127	33
60	51	33	121	32
20	52	34	123	32
25	46	30	108	28
25	45	29	106	28
20	44	29	105	28
25	40	26	94	25
30	48	31	112	30
67	77	50	180	48
84	96	63	226	60
100	114	75	269	71
118	135	88	317	84
80	76	50	180	47
100	96	63	225	59
120	115	75	270	71
140	134	88	315	83
36	34	22	81	21
75	69	45	163	43
106	115	75	271	72
124	135	88	317	84
190	207	136	486	129
122	114	75	269	71
144	135	88	317	84
220	207	135	485	129
Common British basis weights (various paper sizes and ream sizes)	Equivalent weight of a 500‑sheet ream of double imperial paper, a British wrapping paper commonly used to express the basis weight of wrapping paper (rounded to the nearest quarter) (a common British basis for intra‑category comparison)	Equivalent weight of a 500‑sheet ream of demy paper, a British uncut printing paper commonly used by default to express the basis weight of different types of paper (rounded to the nearest quarter) (a common British basis for cross‑category comparison)	Equivalent grammage (rounded to the nearest one)	Equivalent weight of a 500‑sheet ream of bond paper, an American uncut paper commonly used to express the basis weight of paper (rounded to the nearest quarter) (a common American basis for cross‑category comparison)
28	81	24	88	23
40	116	35	125	33
50	41	12	44	11
60	49	14	53	14
70	57	17	62	16
80	65	19	71	18
100	82	24	88	23
120	98	29	106	28
140	115	34	124	33
160	131	39	142	37
13	29	9	32	8
15	34	10	37	9
19	43	13	46	12
23	52	15	56	15
24	54	16	59	15
47	106	32	115	30
80	181	54	195	52
100	226	68	244	65
120	272	82	293	78
34	38	11	42	11
38	43	13	46	12
48	51	15	56	14
120	126	38	136	36
15	51	15	56	14
26	45	13	48	12
29	46	14	50	13
30	51	15	56	14
34	58	17	63	16
60	103	31	112	29
200	141	42	153	40
50	104	31	112	29
60	125	37	135	35
70	145	44	157	41
140	291	88	314	83
60	62	18	67	18
65	67	20	73	19
80	83	25	90	24
100	104	31	112	29
120	125	37	135	35
140	145	44	157	41
160	166	50	180	47
240	250	75	269	71
240	125	37	135	35
280	145	44	157	41
19	56	17	61	16
34	38	11	42	11
38	43	13	46	12
48	51	15	56	14
14	40	12	44	11
15	43	13	47	12
190	450	136	486	129
220	450	135	485	129
32	48	14	53	14
26	31	9	33	8
30	35	10	39	10
42	50	15	54	14
180	134	40	145	38

---

Conversion between British basis weights, American basis weights, and grammage

It is possible to convert between different basis weights – both British and American – and grammage using different conversion formulae.

To convert between the basis weights of different paper with the same basis‑ream size (e. g., from to ), the following formula can be employed: Page 368, November–December, 1894 edition, The British Printer

Area of one sheet of paper in the target ream × Weight of the source ream ÷ Area of one sheet of paper in the source ream

To convert between the basis weights of different paper with different basis‑ream sizes (e. g., from to ), the relevant formula is below:

(Number of sheets of paper in the target ream × Area of one sheet of paper in the target ream) × Weight of the source ream ÷ (Number of sheets of paper in the source ream × Area of one sheet of paper in the source ream)

To convert between the basis weights of the same paper with different basis‑ream sizes (e. g., from to ), one may either use the previous formula or the one below:

Weight of the source ream × Applicable conversion factor from the table below, Paper and Its Uses (1919 edition)

To convert from a basis weight to its equivalent grammage, the following is the applicable formula:, Paper and Its Uses (1939 edition)

Weight of the basis ream × 703,125 ÷ Area of one sheet of paper in the basis ream in square inch × Number of sheets of paper in the basis ream

To convert from grammage to the equivalent basis weight, the formula below can be used:

Area of one sheet of paper in the basis ream in square inch × Number of sheets of paper in the basis ream × Value of gram per square metre ÷ 703,125

Utilising the aforementioned formulae, it is possible to work out the conversion factors for converting between various British and American units of basis weight and the gram per square metre:

+Table of conversion factors for British units of basis weight (standardised basis sizes and 500‑sheet basis reams only) and their metric and American equivalents	Note 1: Value of × Relevant conversion factor = Value of the unit in the left column Note 2: Value of a unit in the left column ÷ Relevant conversion factor = Value of Note 3: To convert between any two units in the left column, Value of the source unit × (Conversion factor for the target unit ÷ Conversion factor for the source unit) Note 4: Note that, as a matter of mathematical relationship, 1 'single' unit (e. g., ) is always equal to 2 'double' unit (e. g., ) and 4 'quad' unit (e. g., ), respectively. By the same token, 1 'double' unit is always equal to 'single' unit and 2 'quad' unit, respectively; and 1 'quad' unit is always equal to 'double' unit and 'single' unit, respectively. Due to the rounding of the conversion factors in this table, calculating with the conversion factors alone may not produce such results automatically.
	(UK)
(UK)	1.219047
(the definition on the island of Great Britain) (UK)	4.205713
(the definition on the island of Ireland) (UK)	4.388570
(UK)	1.523809
(UK)	2
(UK)	6.628570
(UK)	2.742856
(UK)	1.165714
(UK)	3.352380
(UK)	3.314285
(UK)	1.759999
(UK)	2.102856
(UK)	1.447619
(UK)	2.539681
(UK)	1.574603
(UK)	1.110475
(UK)	4.876188
(UK)	0.582857
(UK)	1.676190
(UK)	1.657142
(UK)	0.880000
(UK)	1.405713
(UK)	1.051428
(UK)	0.723809
(UK)	3.047619
(UK)	4
(UK)	2.331429
(UK)	1.269840
(UK)	4.114285
(UK)	0.832857
(UK)	0.740317
(UK)	0.787301
(UK)	0.555237
(UK)	1.158094
(metric)	3.571142
(US)	0.949841
(US)	1.628571
(US)	1.320634
(US)	1.975236
(US)	2.194284
(US)	2.412696

+Table of conversion factors for British units of basis weight (all basis sizes and basis‑ream sizes) and their metric and American equivalents	Note 1: Value of × Relevant conversion factor = Value of the unit in the left column Note 2: Value of a unit in the left column ÷ Relevant conversion factor = Value of Note 3: To convert between any two units in the left column, Value of the source unit × (Conversion factor for the target unit ÷ Conversion factor for the source unit) Note 4: Note that, as a matter of mathematical relationship, as long as the ream size is the same, 1 'single' unit (e. g., ) is always equal to 2 'double' unit (e. g., ) and 4 'quad' unit (e. g., ), respectively. By the same token, 1 'double' unit is always equal to 'single' unit and 2 'quad' unit, respectively; and 1 'quad' unit is always equal to 'double' unit and 'single' unit, respectively. Due to the rounding of the conversion factors in this table, calculating with the conversion factors alone may not produce such results automatically.
	(UK)
(UK)	2.155275
(UK)	2.245079
(UK)	2.263039
(UK)	2.316921
(the pre–‍1937 standardisation definition) (UK)	1.141027
(the pre–‍1937 standardisation definition) (UK)	1.188571
(the pre–‍1937 standardisation definition) (UK)	1.198079
(the pre–‍1937 standardisation definition) (UK)	1.226605
(UK)	1.170285
(UK)	1.219047
(UK)	1.228799
(UK)	1.258056
(definition on the island of Great Britain) (UK)	4.037483
(definition on the island of Great Britain) (UK)	4.205713
(definition on the island of Great Britain) (UK)	4.239357
(definition on the island of Great Britain) (UK)	4.340294
(definition on the island of Ireland) (UK)	4.213026
(definition on the island of Ireland) (UK)	4.388570
(definition on the island of Ireland) (UK)	4.423677
(definition on the island of Ireland) (UK)	4.529003
(UK)	0.804571
(UK)	0.838095
(UK)	0.844799
(UK)	0.864914
(UK)	0.731428
(UK)	0.761905
(UK)	0.768000
(UK)	0.786285
(UK)	0.960000
(UK)	1.008000
(UK)	1.032000
(UK)	2.282055
(UK)	2.377142
(UK)	2.396159
(UK)	2.453210
(UK)	1.462856
(UK)	1.523809
(UK)	1.535999
(UK)	1.572571
(UK)	1.919999
(UK)	2
(UK)	2.015999
(UK)	2.063999
(UK)	6.363425
(UK)	6.628570
(UK)	6.681596
(UK)	6.840682
(UK)	2.633141
(UK)	2.742856
(UK)	2.764798
(UK)	2.830627
(UK)	3.476721
(UK)	3.621586
(UK)	3.650557
(UK)	3.737475
(UK)	1.119085
(UK)	1.165714
(UK)	1.175040
(UK)	1.203017
(UK)	2.594132
(UK)	2.702221
(UK)	2.723838
(UK)	2.788691
(UK)	3.218284
(UK)	3.352380
(UK)	3.379198
(UK)	3.459655
(UK)	3.181712
(UK)	3.314285
(UK)	3.340798
(UK)	3.420341
(UK)	1.689599
(UK)	1.759999
(UK)	1.774079
(UK)	1.816319
(UK)	2.018741
(UK)	2.102856
(UK)	2.119678
(UK)	2.170147
(the pre–‍1937 standardisation definition) (UK)	1.412875
(the pre–‍1937 standardisation definition) (UK)	1.471745
(the pre–‍1937 standardisation definition) (UK)	1.483518
(the pre–‍1937 standardisation definition) (UK)	1.518840
(the pre–‍1937 standardisation definition) (UK)	1.454932
(the pre–‍1937 standardisation definition) (UK)	1.515555
(the pre–‍1937 standardisation definition) (UK)	1.527679
(the pre–‍1937 standardisation definition) (UK)	1.564052
(UK)	1.389714
(UK)	1.447619
(UK)	1.459199
(UK)	1.493942
(UK)	0.914285
(UK)	0.952380
(UK)	0.959999
(UK)	0.982856
(UK)	2.438093
(UK)	2.539681
(UK)	2.559998
(UK)	2.620950
(UK)	2.072379
(UK)	2.158729
(UK)	2.175998
(UK)	2.227808
(UK)	1.511618
(UK)	1.574603
(UK)	1.587199
(UK)	1.624990
(UK)	1.066056
(UK)	1.110475
(UK)	1.119359
(UK)	1.146010
(UK)	1.414095
(UK)	1.473016
(UK)	1.484799
(UK)	1.520152
(UK)	2.223541
(UK)	2.316189
(UK)	2.334718
(UK)	2.620950
(UK)	1.570132
(UK)	1.635555
(UK)	1.648639
(UK)	1.687892
(UK)	1.872456
(UK)	1.950475
(UK)	1.966078
(UK)	2.012890
(UK)	4.681139
(UK)	4.876188
(UK)	4.915196
(UK)	5.032225
(UK)	0.559543
(UK)	0.582857
(UK)	0.587520
(UK)	0.601508
(UK)	1.331199
(UK)	1.386666
(UK)	1.397759
(UK)	1.431039
(UK)	1.609142
(UK)	1.676190
(UK)	1.689599
(UK)	1.729827
(UK)	1.590856
(UK)	1.657142
(UK)	1.670399
(UK)	1.710170
(UK)	0.959999
(UK)	0.999999
(UK)	1.007999
(UK)	1.031999
(UK)	0.844799
(UK)	0.880000
(UK)	0.887039
(UK)	0.908159
(the pre–‍1937 standardisation definition) (UK)	1.316571
(the pre–‍1937 standardisation definition) (UK)	1.371428
(the pre–‍1937 standardisation definition) (UK)	1.382399
(the pre–‍1937 standardisation definition) (UK)	1.415314
(UK)	1.349484
(UK)	1.405713
(UK)	1.416958
(UK)	1.450696
(UK)	0.960000
(UK)	1
(UK)	1.008000
(UK)	1.032000
(UK)	1.009371
(UK)	1.051428
(UK)	1.059839
(UK)	1.085073
(UK)	0.727238
(UK)	0.757540
(UK)	0.763600
(UK)	0.781781
(UK)	0.665295
(UK)	0.693016
(UK)	0.698559
(UK)	0.715192
(the pre–‍1925 standardisation definition) (UK)	0.706437
(the pre–‍1925 standardisation definition) (UK)	0.735872
(the pre–‍1925 standardisation definition) (UK)	0.741759
(the pre–‍1925 standardisation definition) (UK)	0.759420
(the pre–‍1925 standardisation definition) (UK)	0.727466
(the pre–‍1925 standardisation definition) (UK)	0.757777
(the pre–‍1925 standardisation definition) (UK)	0.763839
(the pre–‍1925 standardisation definition) (UK)	0.782026
(UK)	0.694857
(UK)	0.723809
(UK)	0.729600
(UK)	0.746971
(UK)	0.457143
(UK)	0.476191
(UK)	0.480000
(UK)	0.491429
(UK)	2.925713
(UK)	3.047619
(UK)	3.071998
(UK)	3.145141
(UK)	3.839999
(UK)	4
(UK)	4.031999
(UK)	4.127999
(UK)	2.238171
(UK)	2.331429
(UK)	2.350080
(UK)	2.406034
(UK)	5.188263
(UK)	5.404442
(UK)	5.447676
(UK)	5.577383
(UK)	1.828572
(UK)	1.904763
(UK)	1.920000
(UK)	1.965715
(UK)	4.876186
(UK)	5.079362
(UK)	5.119995
(UK)	5.241900
(UK)	2.925712
(UK)	3.047618
(UK)	3.071998
(UK)	3.145140
(UK)	1.219046
(UK)	1.269840
(UK)	1.279999
(UK)	1.310475
(UK)	3.949712
(UK)	4.114285
(UK)	4.147198
(UK)	4.245940
(the pre–‍1925 standardisation definition) (UK)	0.791466
(the pre–‍1925 standardisation definition) (UK)	0.824444
(the pre–‍1925 standardisation definition) (UK)	0.831040
(the pre–‍1925 standardisation definition) (UK)	0.850826
(UK)	0.799543
(UK)	0.832857
(UK)	0.839520
(UK)	0.859508
(UK)	0.710704
(UK)	0.740317
(UK)	0.746240
(UK)	0.764007
(UK)	1.036190
(UK)	1.079364
(UK)	1.087999
(UK)	1.113904
(UK)	0.755809
(UK)	0.787301
(UK)	0.793599
(UK)	0.812495
(UK)	0.533028
(UK)	0.555237
(UK)	0.559679
(UK)	0.573005
(UK)	0.731428
(UK)	0.761905
(UK)	0.768000
(UK)	0.786285
(UK)	0.938666
(UK)	0.977777
(UK)	0.985599
(UK)	1.009066
(UK)	0.654018
(UK)	0.681269
(UK)	0.686719
(UK)	0.703070
(UK)	1.111770
(UK)	1.158094
(UK)	1.167359
(UK)	1.195153
(the pre–‍1925 standardisation definition) (UK)	1.267199
(the pre–‍1925 standardisation definition) (UK)	1.319999
(the pre–‍1925 standardisation definition) (UK)	1.330559
(the pre–‍1925 standardisation definition) (UK)	1.362239
(the pre–‍1925 standardisation definition) (UK)	1.374475
(the pre–‍1925 standardisation definition) (UK)	1.431745
(the pre–‍1925 standardisation definition) (UK)	1.443199
(the pre–‍1925 standardisation definition) (UK)	1.477561
(UK)	1.250742
(UK)	1.302856
(UK)	1.313279
(UK)	1.344547
(UK)	1.170285
(UK)	1.219047
(UK)	1.228799
(UK)	1.258056
(UK)	1.365333
(UK)	1.422222
(UK)	1.433599
(UK)	1.467733
(UK)	1.587199
(UK)	1.653333
(UK)	1.666559
(UK)	1.706239
(UK)	1.740799
(UK)	1.813333
(UK)	1.827839
(UK)	1.871359
(UK)	1.716418
(UK)	1.787936
(UK)	1.802239
(UK)	1.845149
(UK)	1.877332
(UK)	1.955555
(UK)	1.971198
(UK)	2.018132
(UK)	1.906589
(UK)	1.986031
(UK)	2.001918
(UK)	2.049583
(UK)	1.755427
(UK)	1.828571
(UK)	1.843199
(UK)	1.887084
(UK)	2.106512
(UK)	2.194284
(UK)	2.211838
(UK)	2.264501
(UK)	2.340569
(UK)	2.438094
(UK)	2.457598
(UK)	2.516112
(UK)	2.282056
(UK)	2.377142
(UK)	2.396159
(UK)	2.453210
(UK)	3.071998
(UK)	3.199999
(UK)	3.225598
(UK)	3.302398
(UK)	3.111008
(UK)	3.240634
(UK)	3.266558
(UK)	3.344333
(UK)	2.779426
(UK)	2.895237
(UK)	2.918398
(UK)	2.987883
(UK)	3.364569
(UK)	3.504761
(UK)	3.532798
(UK)	3.616912
(UK)	2.984227
(UK)	3.108571
(UK)	3.133438
(UK)	3.208044
(UK)	3.159770
(UK)	3.291428
(UK)	3.317758
(UK)	3.396752
(UK)	4.213026
(UK)	4.388570
(UK)	4.423677
(UK)	4.529003
(UK)	4.447083
(UK)	4.632379
(UK)	4.669437
(UK)	4.780614
(UK)	6.143996
(UK)	6.399998
(UK)	6.451196
(UK)	6.604796
(metric)	3.571142
(US)	0.949841
(US)	1.628571
(US)	1.320634
(US)	1.975236
(US)	2.194284
(US)	2.412696

Using British basis sizes and the 500‑sheet basis‑ream (a traditional British basis‑ream size that coincides with the modern standard definition of 'ream'), and with the help of the aforementioned conversion formulae or conversion factors, it is possible to express the paper weights of different types of paper in everyday life using British units of basis weight: the typical photocopier paper that is used as all‑purpose paper is 17 or 19 (70 or 80gsm); GSM Paper: the Complete Guide personal and business letter paper, especially that with engraved letterheads, is typically 24–29 (100–120gsm);' What is GSM Paper Weight?', Solopress Blog greetings cards are usually 85–106 (200–250gsm);' Understanding the Different gsm Weights for Card and Paper Supplies', Mankey Monkey newspaper paper is typically 15–23 (35–55gsm);' Paper GSM Guide', The Paperbox Limited business cards are usually 128–149 (300–350gsm); /ref> In the traditional British system, large post, double crown, and double imperial are common British basis sizes for writing paper, printing paper and other paper that is not writing or wrapping paper, and wrapping paper, respectively. '500' is omitted because it is clear from the context that a 'ream' is 500 sheets.

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Caliper

Paper thickness, or caliper, is a common measurement specified and required for certain printing applications. Since a paper's density is typically not directly known or specified, the thickness of any sheet of paper cannot be calculated by any method. Instead, it is measured and specified separately as its caliper. However, paper thickness for most typical business papers might be similar across comparable brands. If thickness is not specified for a paper in question, it must be either measured or guessed based on a comparable paper's specification.

Caliper is usually measured in micrometres (μm), or in the United States also in mils (1 mil =  in = 25.4 μm). Commonly, 20-pound bond paper ranges between roughly in thickness.

The paper density is calculated by dividing the grammage over the caliper, and is usually expressed in grams per cubic centimetre (g/cm³) to cancel out the mathematical need for between and micrometres (a conversion factor of 1,000,000).

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See also

• Density
• Area density
• Linear density

• Envelope size
• Hole punch — filing holes
• Index card
• Paper and ink testing
• Photo print sizes

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Notes

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External links

• Understanding Paper Weights
• Understanding paper weight (Staples, Inc.)
• M-weight Calculator
• Paper Weight Calculator
• Paper Weight Conversion GSM to LBS

Categories: Paper, Printing

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