A6

The A6 paper size is one of the smallest formats in the A series defined in the ISO 216 standard. With tiny dimensions of 105 mm x 148 mm, the A6 sheet has an area of 0.015625 square meters. The A6 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 A6 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 A6 format itself was formalized in the early 20th century German standards that led to the ISO standard published in 1975. The tiny A6 is well-suited for postcards, greeting cards, and short letters. Its compact size also allows multiple A6 pages to fit within an A4 document. The portability and versatility of A6 paper make it handy for notes and messages.