Paper Sizes

A sizes

Throughout Britain and Europe metric ISO 'A' sizes are the most common. The first defined size is 'A0' which has an area of one square metre. Folding this sheet in half with give you an 'A1' sheet, folding an 'A1' sheet in half gives you an 'A2' sheet, and so on. As the height and width are in the ratio, one to the square root of two, the proportion of the sheets remains the same. This feature makes it very simple to adapt one design for several different purposes (for example a postcard, leaflet and poster).

Because 'A' sizes are so widely used 'A' size paper is relatively cheap and many machines are optimised for handling them, so 'A' sizes are often the most cost-effective option.

(*often set to 148.5 mm wide)
Here is the same information as a diagram:

Another commonly used size based on the 'A' size system is one third of 'A4' (99 x 210 mm). Two thirds of 'A4' (198 x 210 mm) is also sometimes used as is the square size 210x210mm. There is also 'A00' (or '2A') at 1189 x 1682 mm.

Oversize RA and SRA sizes

Printing presses cannot print right to the edge of a sheet because the excess ink build up would cause problems. Most printers use oversized sheets which are later trimmed down to the finished size.

There are several reasons for having this extra space. It is used for trim, register and colour control marks and where images print to the edge of a document they should continue off the trim area to form a 'bleed' (the standard is 3mm). Where several pages (e.g. of a book) are arranged together on one sheet 'gutters' may be required between pages to allow for folding and trimming. Additionally, about 6-12mm is generally required on one long edge for the 'grippers' which hold the paper as it passes through the machine; this area cannot be printed on at all.

The 'RA' sizes are slightly larger than 'A' sizes but do not generally allow enough space for bleed or colour control marks. Although 'RA' sizes are sometimes used for books, 'SRA' sizes, which allow even more extra space, are much more widely encountered. 'SRA2' (450 x 640 mm) is probably the most commonly used paper size in Britain (because of this it is usually relatively cheap), while 'SRA1' (640 x 900 mm) and 'SRA3' (320 x 450 mm) are also common.

B sizes

The 'B' sizes are designed to be intermediate between the 'A' sizes; their sides are in the same ratio and they are scaled in the same way. They are less frequently used, but can be very useful.

'B1' or 'B2' presses are fairly widely installed and 'B5' is a particularly useful book size. The size specification of a notionally 'B5' book is often not strictly observed. Most 'B2' presses will print a maximum sheet size of 520 x 720 mm which is not really large enough to print eight full 'B5' pages with bleed and gutters. Slightly smaller page sizes such as 173 x 244 mm or 170 x 240 mm are often encountered.

C sizes and envelopes

The main use of the intermediate 'C' size is for envelopes: an 'A4' sheet will fit into a 'C4' envelope, an 'A6' sheet into a 'C6' envelope and so on.

Perhaps the most commonly encountered envelope size is 'DL' (220x110mm) which neatly fits a sheet of A4 stationery folded into three, or a one third A4 size leaflet.

Envelopes are available in several different types and sizes. Those described as 'wallet' or 'pocket' will open on the long edge, while 'banker' envelopes open on the short edge. Envelopes are also available with address windows and with various self sealing systems.

It is sensible to check the availability of envelopes before using non-standard paper sizes. Many unusual sizes are produced but there is no guarantee that an envelope is available off-the-shelf to fit a particular size. Some sizes are only manufactured in manilla, with windows, or in banker format. For peculiarity papers off-the-shelf envelopes sizes are usually restricted or non-existent. It is usually possible to have an envelope made to any size by the paper manufacturer or a specialist, but the minimum order/charge can prove prohibitive for some projects.

British and US sizes

There are many British Standard paper sizes, whose dimensions are defined in inches, with obscure names such as 'foolscap', 'post', 'pinched post', 'medium', 'royal, crown', 'quad crown' or 'double imperial'. Although these sizes do not preserve their proportions when folded down as 'A' or 'B' sizes do, they do conform to a system of sorts based on folding in half. When a book is printed on a large sheet of paper folded once it is described as a 'folio', when the sheet is folded again it becomes a 'quarto' with four leaves, then an 'octavo', then a '16mo' and so on.

One of the most common sizes used in Britain is 'Foolscap'. This size is based on a large sheet of 13.5 x 17 inches, which as a folio becomes 13.5 x 8.5 inches, as a quarto 6.75 x 8.5 inches and as an octavo 6.75 x 4.25 inches. There is also 'double foolscap' at 17 x 27 inches.

Other British Standard sheets include 'large post' at 16.5 x 21 inches, 'demy' at 17.5 x 22.5 inches, 'royal' at 20 x 25 inches and 'double crown' at 20 x 30 inches to name but a few. With all the folio, quarto and octavo variants of these there are almost endless possibilities. To confuse matters further terms like 'foolscap' and 'quarto' are also used loosely to describe standard stationery sizes, now largely obsolete, while 'imperial' describes not only a paper size, but the system it is measured in.
The United States have a wide range of similar but, evidently, different paper sizes measured in inches. Metric sizes and the metric system as a whole are much less commonly used in the US. However, because most publishing software comes out of the States, it tends to use the US paper sizes by default, so the rest of the world will be familiar with 'US letter' (8.5 x 11 inches), 'US legal' (8.5 x 14 inches) and 'tabloid' (11 x 17 inches).

Although for general printing these sizes have now largely been replaced by the standard metric sizes, they do survive in a few niche areas and are commonly used in book production. In part this is because large book presses and long-running series of books originated before metrication, but it is also because the dimensions and proportions of the 'A' size range are by no means ideal for book production. For example, 'A5' is often considered rather too wide in relation to it's height to be visually pleasing and is slightly too wide to fit easily into the average pocket. The next size down is 'A6', which would be too small for the majority of books.

Calculating weights

Paper weights are calculated using gramme's per square metre (gsm). The most common weight used for covers is 200gsm and above, and text paper ranges from 50gsm to 170gsm. The approximate weight of a publication can be calculated based on the finished size, the total number of pages and the paper weight used for the text and cover. To calculate this the following formula can be used.

Height x Width x (No. of Pages) / 2 * (Paper Weight) / 1,000,000