A8

The A8 paper size is an extra-small format in the A series defined in the ISO 216 standard. With tiny dimensions of 52 mm x 74 mm, the A8 sheet has an area of 0.00390625 square meters. The A8 size was developed as part of the A series based on the aspect ratio of √2, enabling each size to neatly fold down from the larger sheets.

The origins of A8 date back to the late 18th century in Germany along with the other A series sizes. The √2 aspect ratio was first proposed in a 1786 letter by German scientist Georg Christoph Lichtenberg. This geometric ratio allowed for the creation of the A series with its ability to smoothly scale sizes up and down by folding sheets in half. The miniscule A8 format itself was formalized in the early 20th century German standards that led to the ISO standard published in 1975. The very compact A8 is well-suited for small labels, stamps, and thin booklets. Its tiny dimensions allow multiple A8 pages to easily fit within larger A series sizes. The extremely small nature of A8 paper makes it useful when space is severely constrained.