‘A’ sizes
In all countries using the metric system, ISO ‘A’ sizes are the most common. The starting point is an ‘A0′ sheet with an area of one square meter. Folding this sheet in half results in an ‘A1′ sheet, folding an ‘A1′ sheet in half gives an ‘A2′ sheet, and so on. Because 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).
| Size | Dimensions | Uses |
| A0 | 841 mm x 1189 mm | posters |
| A1 | 594 mm x 841 mm | posters |
| A2 | 420 mm x 594 mm | posters, calendars |
| A3 | 297 mm x 420 mm | posters, calendars, ‘tabloid’ magazines |
| A4 | 210 mm x 297 mm | stationery, books, annual reports |
| A5 | 148 mm x 210 mm | personal stationery, books, brochures, leaflets |
| A6 | 148 mm x 105 mm | postcards, leaflets, invitations, booklets |
| A7 | 105 mm x 74 mm | tickets |
Here is the same information as a diagram:
DL sizes: 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.
