A0

The A0 paper size is the largest format in the A series defined by the ISO 216 international standard. With dimensions of 841 mm x 1189 mm, the A0 sheet has a surface area of 1 square meter. The origins of A0 date back to the late 18th century in Germany, when scientists proposed basing paper sizes on an aspect ratio of √2 to enable efficient scaling by folding sheets in half. This geometry was later adopted in the German national standard that led to the formalization of A0 as the base size for the A series.

Its spacious dimensions make A0 suitable for very large posters, technical drawings, and charts. The standardization of A0 and other A sizes allowed for ease of scaling between document sizes, facilitating activities like photocopying and printing across the A series formats. The roots of A0 trace back to a 1786 letter by German scientist Georg Christoph Lichtenberg that proposed the √2 aspect ratio. This geometric ratio was then adopted in the early 20th century German standard that became the basis for the international ISO 216 standard published in 1975. Overall, the origins of A0 demonstrate how mathematical principles were applied to create an integrated system of paper sizes that could scale up and down smoothly for over 200 years.