PA1

The PA1 paper size has dimensions of 560mm x 840mm, giving it a total surface area of 0.4704 square meters. As part of the PA transitional paper size system proposed in 1975, PA1 serves as a size between the very large PA0 and the standard A1 format from ISO 216. With its narrower width of 560mm, PA1 lends itself better to certain use cases compared to PA0, while still providing ample area for sizable charts, presentation slides, or posters. Its 1:√2 aspect ratio mirrors standardized formats, allowing efficient scaling. PA1 has no well known alternative names, but its dimensions correspond roughly to the width of Arch E and height of Arch D paper sizes. Like other PA series formats, PA1 was conceived to fill gaps left by ISO standard sizes for niche applications. Its backstory lacks the rich history of the A or B series, but PA1 has demonstrated utility nonetheless for contexts demanding a transitional size between PA0 and A1. With considerable area and similar proportions to common standards, PA1 adapts well as an outsized version of A1 for special use cases. Though originally rejected alongside the rest of the PA series for ISO standardization, PA1 persists as a helpful large-format option where the traditional sizes leave something to be desired.