a4( 16k)297mm×2 10mm；
a5(32k)2 10mm× 148mm；
a6(64k) 144mm× 105mm；
A3(8k) size has not been determined, and it is generally 420mm×297mm.
The format size stipulated by the state is an international standard series, which has been included in the national industry standard GB/T 788- 1999 "Format Size of Books and Periodicals".
Extended data
According to the size, folio is usually divided into three types: large format, medium format and small format.
For 787× 1092 paper, 12 format is large format, 16 ~ 36 format is medium format, and 40 format is small format, but books with mainly characters are generally medium format. Folio shapes are rectangles with different proportions except 6 quarts, 12 quarts, 20 quarts, 24 quarts and 40 quarts, which are suitable for books with different properties and uses.
Baidu encyclopedia-folio size