A7

The A7 paper size is one of the smallest format in the A series defined in the ISO 216 standard. With miniscule dimensions of 74 mm x 105 mm, the A7 sheet has an area of 0.0078125 square meters. The A7 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 A7 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 tiny A7 format itself was formalized in the early 20th century German standards that led to the ISO standard published in 1975. The extremely compact A7 is well-suited for small labels, tags, and index cards. Its tiny dimensions allow multiple A7 pages to easily fit within larger A series sizes. The diminutive nature of A7 paper makes it ideal for uses requiring minimal space.