What people mean when they talk about the weight of a sheet of paper or card is effectively the thickness of that piece of paper. There are two conventions currently in widespread use for paper weights.

The first, as specified by ISO 536, is used in Europe and most parts of the world that use ISO paper sizes, apart from the few countries that still use US paper sizes, is grams per square metre (g/m² or commonly gsm). This commonly called grammage in non English speaking countries, a term we will use on this site to differentiate it from the North American basis weights.

The second is used in those countries that use US paper sizes such as the United States and Canada. This is known as the basis weight and is usually specified in pounds (lbs). The basis weight is the weight of a 500 sheet ream of uncut paper (see Reams & Quires - Paper Quantities Explained for more information on the ream).

Grammage

The weight of paper in countries that use ISO paper sizes is defined by ISO 536 Paper and Board - Determination of Grammage. This standard defines grammage as grammes per square metre (g/m²) thus the weight of a single sheet of A0 paper defines the grammage of that paper type as the A0 size is defined by ISO 216 as having an area of 1 square metre. An A0 sheet of 80gsm paper will weigh 80 grams, an A0 sheet of 100gsm paper will weigh 100 grams and so on.

Note gsm is commonly used rather than g/m² in most day to day use. This came about because of the inability of early computer packages to display superscripted characters - especially stock control, accounting and invoicing systems.

Paper that is used in offices is usually between 70gsm and 80gsm, with 80gsm being the most commonly found weight. Some accountants and solicitors use heavier weight paper ranging from 90gsm to 120gsm for formal correspondance. Above 120gsm come various thicknesses of card with 160gsm and 200gsm being most commonly used for file dividers. Newspaper ranges between 45gsm and 50gsm.

Weight of Sheets & Reams Calculator

Click the link for a table of weights of individual sheets of 4A0, 2A0, A0, A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10 for various commonly used grammages.

Basis Weight

Basis weight is a much older convention for defining the weight of paper and was widely used in the UK and Europe as well as in North America, where it is still used, up until the international standardisation of paper sizes by ISO 216 and its national predecessors in European countries.

Basis weight is defined as the weight of a ream of the uncut paper in pounds (lb) (Note: the # is often used in place of lb when referring to basis weights). The uncut paper sizes being the size used in the manufacturing process before the paper was cut to size. There are many different types of uncut paper, those in common use for the production of office paper and card are Bond Stock, Cover Stock and Index Stock. The word Stock is often dropped when referring to the different types of paper in their finished cut sizes.

Thus if you have a sheet of 20lb Bond Letter paper it will be the exactly the same thickness as 20lb Bond Legal, although the two sheets will weigh different amounts because of the difference in size. However a sheet of 28lb Bond Letter size paper would not be the same as a sheet of 28lb Cover Letter size paper as the uncut sizes for Bond and Cover are different.

Paper that is used in offices is most commonly 20lb or 24lb Bond. Often suppliers will omit the words Bond and just give the basis weight as 20lb or 24lb, although Index and Cover are almost invariably used as this differentiates the other types from the 'default' Bond. 60lb and 65lb Cover and 90lb and 110lb Index are types of light to medium card often used as file dividers, with 80lb, 90lb and 100lb Cover being heavier weight card.

Newspaper has its own stock type, Newsprint, that measures 24" x 36" in uncut size. This is much larger than the Bond and Cover uncut sizes, thus the most common 30lb Newsprint is actually a much thinner paper than 20lb bond. The following page covers the different stock types generally available.

Conversion tables for Basis Weight to Grammage Conversion

The weight of a sheet of paper depends on the size of the sheet and the thickness of the paper, known as grammage internationally and basis weight in North America. The tables below give the weights of sheets of the ISO 216 A paper sizes for various common grammages (e.g. 80gsm, 90gsm, 120gsm) in grams in the first table and in ounces in the second table.

The ISO A series paper sizes are 4A0, 2A0, A0, A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10, see A Paper Sizes for more information and here for US Paper Sizes.

Weights Of Sheets Of A Series Paper Sizes In Grams

Size	75gsm	80gsm	90gsm	100gsm	110gsm	120gsm	160gsm
4A0	300g	320g	360g	400g	440g	480g	640g
2A0	150g	160g	180g	200g	220g	240g	320g
A0	75g	80g	90g	100g	110g	120g	160g
A1	37.5g	40g	45g	50g	55g	60g	80g
A2	18.75g	20g	22.5g	25g	27.5g	30g	40g
A3	9.38g	10g	11.25g	12.5g	13.75g	15g	20g
A4	4.69g	5g	5.63g	6.25g	6.88g	7.5g	10g
A5	2.34g	2.5g	2.81g	3.13g	3.44g	3.75g	5g
A6	1.17g	1.25g	1.41g	1.56g	1.72g	1.88g	2.5g
A7	0.59g	0.63g	0.70g	0.78g	0.86g	0.94g	1.25g
A8	0.29g	0.31g	0.35g	0.39g	0.43g	0.47g	0.63g
A9	0.15g	0.16g	0.18g	0.20g	0.21g	0.23g	0.31g
A10	0.07g	0.08g	0.09g	0.10g	0.11g	0.12g	0.16g

 

Weights Of Sheets Of A Series Paper Sizes In Ounces

Size	75gsm	80gsm	90gsm	100gsm	110gsm	120gsm	160gsm
4A0	10.582oz	11.288oz	12.699oz	14.110oz	15.521oz	16.932oz	22.575oz
2A0	5.291oz	5.644oz	6.349oz	7.055oz	7.760oz	8.466oz	11.288oz
A0	2.646oz	2.822oz	3.175oz	3.527oz	3.880oz	4.233oz	5.644oz
A1	1.323oz	1.411oz	1.587oz	1.764oz	1.940oz	2.116oz	2.822oz
A2	0.661oz	0.705oz	0.794oz	0.882oz	0.970oz	1.058oz	1.411oz
A3	0.331oz	0.353oz	0.397oz	0.441oz	0.485oz	0.529oz	0.705oz
A4	0.165oz	0.176oz	0.199oz	0.220oz	0.243oz	0.265oz	0.353oz
A5	0.083oz	0.088oz	0.099oz	0.110oz	0.121oz	0.132oz	0.176oz
A6	0.041oz	0.044oz	0.050oz	0.055oz	0.061oz	0.066oz	0.088oz
A7	0.021oz	0.022oz	0.025oz	0.028oz	0.030oz	0.033oz	0.044oz
A8	0.010oz	0.011oz	0.012oz	0.014oz	0.015oz	0.017oz	0.022oz
A9	0.005oz	0.006oz	0.006oz	0.007oz	0.007oz	0.008oz	0.011oz
A10	0.002oz	0.003oz	0.003oz	0.004oz	0.004oz	0.004oz	0.006oz