The most widely used paper size and format, the A series papers are most used for office stationery, business publications, as well as communication and promotional materials. It consists of a logical set of paper sizes that are defined by the International Standard for paper sizes ISO 216. In fact, you’ve most likely used an A series size paper many times, perhaps without realizing it.
A4, one of the formats in this series, is considered the most common paper size in the world outside the United States, Canada and Mexico.
A0, the largest in this series, measures 84.1 x 118.9 cm. The succeeding sizes A1 to A10 are based on each size being half the size of the previous one when folded. This also means that the length of one size is equal to the width of the size bigger to it. The quotient of the length divided by the width is 1.4142, and the series’ aspect ratio is 1:√2.
This size format offers useful applications such as enlarging and reducing images without any cutoff or margins. It can also be used to make a booklet by folding sheets in half.