D1

With dimensions of 545 mm x 771 mm, D1 serves as the second largest format in the D series of DIN 476. Its area comes out to 0.42 square meters - exactly half that of the expansive D0 base size. The width-to-height ratio of 1.25 provides an elongated, portrait layout well-suited for technical specifications and administration documents. In particular, the D1 page accommodated French military maps adopted before the country transitioned to ISO standards in the latter 20th century. The aeronautics industry also utilized the size for aircraft drawings and schematics.

Like its larger counterpart, the origins of D1's dimensions likely stemmed from existing German, and perhaps Prussian, graphical formats predating the 1922 DIN 476 release. As cutting and printing equipment became more precise, very large sheets gave way to standardized dimensions better catering to bookbinding, correspondence, storage, and mass publication needs. So while technical document applications persisted, the D series saw declining favor relative to the ISO equivalents. However, the harmonic scaling principles exemplified by halving D0 to reach D1 set the foundation for proliferating incremental paper sizes.