ISO Paper Sizes
The international system for paper sizing is the ISO System which is different from the American national standard (ASME) of Letter, Tabloid, and Legal. The system instead includes A, B, and C series of paper sizes and is the global standard. ISO stands for the International Organization of Standardization, and the abbreviation is used for being language independent and derived from “isos” meaning “equal” in Greek.[1] The ISO system implements ratios and math using the metric system to set proportional paper sizes. The height to width ratio for every size is √2 (1.4142) meaning that two smaller pieces of paper side by side would equal the next largest paper size.[2]
Purpose of Standard Sizes
Standardizing paper makes printing across publishers and printers consistent and allows for easier communication between parties. Paper size standards are used for printed material but also digital documents. This cohesion simplifies printing, scaling, and reproduction. The most common paper size is A4 measuring 210mm by 297mm (close in size to ASME’s 8.5” x 11”) which is used in daily life for flyers, brochures, magazines, and more.[3] In publishing, these standards are used for ease of print production and imposition layout, the prepress process of arranging pages in signatures.
How It Works
The ISO paper system is based on the √2 which allows a sheet of paper to be folded or scaled and still maintain the same proportions. The base size of the A Series is A0 which measures 841mm by 1189mm.[1] Each consecutive size is halved from there with A1 being 594mm by 841mm, A2 being 420mm by 594mm, and so on.[1] In each series, the number after the letter represents the number of times the size was halved from the base size of 0.[1] For sizes that are larger than the base size of 0, a number is added to the beginning to signify it was doubled.[1] For example, 2A0 measures 1189mm by 1682mm.
The A, B, and C Series
The most commonly used sizes come from the A series, but there is also the B and C Series. These sizes also follow the √2 ratio rule.
B Series paper covers a wider variety of paper sizes and is defined by the geometric mean between two A Series sizes.[2] For example, A3 is 297mm by 420mm and A4 is 210mm by 297mm, so B4 is 250mm by 353mm serving as an in-between paper size option.
C Series paper functions mainly for envelopes to fit A Series paper and is defined by the geometric mean between an A Series size and a B Series size.[2] Each A Series paper size will fit into its corresponding C Series envelope, A4 in a C4 envelope etc.
- ↑ 1.0 1.1 1.2 1.3 1.4 Boyce, Mark. Sizes May Vary, a Workbook for Graphic Design. Laurence King Publishing Ltd, 2008.
- ↑ 2.0 2.1 2.2 Kuhn, Markus. “A4 Paper Format / International Standard Paper Sizes.” Cam.ac.uk, 2018, www.cl.cam.ac.uk/~mgk25/iso-paper.html.
- ↑ Adobe. “A4 Paper Size & Uses.” Www.adobe.com, 2024, www.adobe.com/uk/creativecloud/design/discover/a4-format.html.
