Book Size Information

Paper sizes

This list of the common American and European paper sizes includes the ISO standards, which are used globally. All dimensions are specified in inches and millimetres

The ISO A series is the most frequently used page measurement standard.

ISO A paper sizes

The A-series consists of a logical set of paper sizes that are defined by the ISO 216 standard. The largest size (A0) measures one square meter. The height/width ratio remains constant (1:1.41) for all sizes. This means you get the A1 size by folding an A0 paper in two along its shortest side. Then fold the A1 size in two to get an A2 size paper, and so on… A-sizes are used to define the finished paper size in commercial printing: A4 is for office documents, A5 is for notepads and A6 is for postcards.

Reference : http://www.prepressure.com/library/paper-sizes