The basic rule to remembering paper sizes is that as the sheet becomes smaller, the number becomes bigger. For example A4 folded in half becomes A5. The dimensions of the A series paper sizes, as defined by ISO 216, are shown in the table below.
ISO 216 specifies tolerances for the production of A series paper sizes as follows:
• ±1.5mm for dimensions up to
• ±2.0mm for lengths in the range 150 to 600mm.
• ±3.0mm for any dimension above 600mm.
The A series paper sizes are defined in ISO 216 by having the following requirements:
• The length divided by the width is 1.4142.
• The A0 size has an area of 1 square metre.
• Each subsequent size A(n) is defined as A(n-1) cut in half parallel to its shorter sides.
• The standard length and width of each size is rounded to the nearest millimetre.
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