Editing Paper size (section)

===B series<span class="anchor" id="ISO B"></span><span class="anchor" id="DIN B"></span><span class="anchor" id="SIS B"></span>===
[[File:B size illustration2.svg|thumb|right|A size chart illustrating the ISO B series]]

The B series paper sizes are less common than the A series. They have the same aspect ratio as the A series:

<math>\frac{a}{b}=\sqrt{2} = 1.41421...</math>

However, they have a different area. The area of B series sheets is in fact the [[geometric mean]] of successive A series sheets. B1 is between A0 and A1 in size, with an area of <math>\frac{1}{\sqrt{2}}</math> m{{sup|2}}, or about {{cvt|0.707|m2}}. As a result, B0 is 1 metre wide, and other sizes of the series are a half, a quarter, or further fractions of a metre wide: in general, every B size has exactly one side of length <math>\frac{1 \operatorname{m}}{2^n}</math> for <math>n \in \mathbb{N}</math>. That side is the short side for B0, B2, B4, etc., and the long side for B1, B3, B5, etc.

While less common in office use, the B series is used for a variety of applications in which one A-series size would be too small but the next A-series size is too large, or because they are convenient for a particular purpose.

* B4, B5, and B6 are used for [[envelope]]s that will hold C-series envelopes.
* B4 is quite common in printed music sheets.
* B5 is a relatively common choice for books.
* B7 is equal to the passport size ID-3 from [[ISO/IEC 7810]].
* Many posters use B-series paper or a close approximation, such as 50&nbsp;cm × 70&nbsp;cm ~ B2.

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The B-series is widely used in the printing industry to describe both paper sizes and [[printing press]] sizes, including [[digital printing|digital presses]]. B3 paper is used to print two US letter or A4 pages side by side using [[imposition]]; four pages would be printed on B2, eight on B1, etc.{{qn|date=January 2020}}