JIS B series

The Japanese standard JIS P 0138-61 adopts the A and C series of ISO and DIN, respectively, but defines a slightly different B series: JIS B0 has an area of 1.5 m², the arithmetic and non-geometric mean of the areas of A0 and 2A0, widths and heights are determined analogously to A and rounded accordingly.

The origin of the Japanese B series lies in the fact that this format was intended to be compatible with the already used Shiroku-ban with its dimensions of 127 × 188 mm, which in turn had its origin in the officially used Mino-ban format of the Edo period. The Shiroku-ban thus became almost identical to the new JIS B6.