Paper size

Summary

Paper size standards govern the size of sheets of paper used as writing paper, stationery, cards, and for some printed documents. Most countries adhere to the ISO 216 standard, which includes the widely recognized A series, defined by a consistent aspect ratio of √2. The system, first proposed in the 18th century and formalized in 1975, allows scaling between sizes without distortion. Regional variations exist, such as the North American paper sizes which are governed by the ANSI and are used in North America and parts of Central and South America.