A Series
ISO 216 Standard and the A Series
The ISO 216 standard defines the A series, the most widely recognized international system for paper dimensions. The A series is the standard used all around the world apart from USA, Canada and some other countries.
Main Characteristic
The defining characteristic of the A series is its aspect ratio of 1:√2 (approximately 1:1.414). This specific geometry ensures that when a sheet is folded or cut in half parallel to its shorter side, the resulting two sheets maintain the exact same proportions as the original. This allows for seamless scaling; for instance, an A4 design can be enlarged to A3 or reduced to A5 without any distortion of the layout or margins.
Measurement System
Starting Point: The series begins with A0, which is defined as having a total surface area of exactly one square meter (1m2).
Scaling: Each subsequent size is derived by halving the area of the preceding one: A1 is half of A0, A2 is half of A1, and so on.
Common Usage: The most ubiquitous size, A4 (210 x 297 mm), serves as the global standard for business letters and personal printing.