C8 paper size in mm

What is C8 paper size in mm ?

C8 size in mm is 57x81

The aspect ratio of an C8 paper is 1:1.42,The area of an C8 paper is 4617 mm², Perimeter of an C8 paper is 276 mm, Diagonal line of an C8 paper is 99.05 mm

Millimeter is a unit of length and a unit of rainfall, abbreviated in English as mm. 1mm=0.1cm=0.01dm=0.001m=0.000001km=1 000μm=1 000 000nm