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Print Design: ISO sizes Paper & Envelopes


In the ISO paper size system, the height-to-width ratio of all pages is the square root of two (1.4142 : 1). In other words, the width and the height of a page relate to each other like the side and the diagonal of a square. This aspect ratio is especially convenient for a paper size.

If you put two such pages next to each other, or equivalently cut one parallel to its shorter side into two equal pieces, then the resulting page will have again the same width/height ratio.

The ISO paper sizes are based on the metric system. The square-root-of-two ratio does not permit both the height and width of the pages to be nicely rounded metric lengths. Therefore, the area of the pages has been defined to have round metric values. As paper is usually specified in g/m≤, this simplifies calculation of the mass of a document if the format and number of pages are known.

ISO Sizes A series

ISO CodeSize in millimetersSize in inchesSize in Points
A0841 x 118933 x 46.812384 x 3370
A1594 x 84123.39 x 331684 x 2384
A2420 x 59416.54 x 23.361191 x 1684
A3297 x 42011.69 x 16.54842 x 1191
A4210 x 2978.27 x 11.69595 x 842
A5148 x 2105.83 x 8.27420 x 595
A6105 x 1484.13 x 5.83298 x 420
A774 x 1052.91 x 4.13210 x 298
A852 x 742.05 x 2.91147 x 210

The B series formats are geometric means between the A series format with the same number and the A series format with one lower number. For example, B1 is a geometric mean between A1 and A0. The sides of B0 are 1 m to v2 m.

ISO Sizes B series

ISO CodeSize in millimetersSize in inchesSize in Points
B01000 x 141433.37 x 55.672836 x 4008
B1707 x 100027.84 x 39.372004 x 2835
B2500 x 70719.69 x 27.841417 x 2004
B3353 x 50013.9 x 19.691001 x 1417
B4250 x 3529.84 x 13.9709 x 1001
B5176 x 2506.93 x 9.84499 x 709
B6125 x 1764.92 x 6.93354 x 499
B788 x 1253.47 x 4.92249 x 354
B862 x 882.44 x 3.47176 x 249

The current ISO 216 standard was introduced in 1975 and is a direct follow up to the german DIN 476 standard from 1922. The Netherlands have used the DIN/ISO standard since 1925, Belgium since 1924, England (UK) since 1959 and France since 1967. ISO 216 is also called EN 20216 in Europe.

ISO envelopes

ISO sizes C series – Envelopes

International standard ISO (International Organization for Standardization) 269 defines several standard envelope sizes, which are designed for use with ISO 216 standard paper sizes (the A series). The German standard DIN 678 defines a similar list of envelope formats. This envelope series was designed to accommodate ISO A size papers. Metric measurements are the finished envelope size. Inch measurements are approximate.

NameSize in millimetersSize in inchesUsage and comments
C0917 x 129736.12 x 51.6For flat A0.
C1648 x 91725.50 x 26.12For flat A1, A0 folded in half.
C2458 x 64818 x 25.50For flat A2, A1 folded in half.
C3324 x 45812.75 x 18For flat A3, A2 folded in half.
C4229 x 3249 x 12.75For flat A4, A3 folded in half.
C5162 x 2293.37 x 9For flat A5, A4 folded in half.
C6114 x 1624.5 x 6.37For A5 folded in half.
DL110 x 2204.32 x 8.69For A4 folded (in thirds), A5 in half.

Although DL is not part of the ISO C series, it is a very widely used standard size. DL, probably at one time the abbreviation of DIN Lang (Deutsche Industrie Norm, Long), is now identified as “Dimension Lengthwise” by ISO 269.


Author: Jan Rajtoral

Jan Rajtoral AKA Gonzo the Great is the Founder of and Designer at gonzodesign, providing design services across the full spectrum of Brand Identity, Graphic Design, Print and Advertising Design & Website Design.


on this article: “Print Design: ISO sizes Paper & Envelopes”
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