Below is a list of standard ISO 216 Paper Sizes. All sizes are in millimetres.

Paper Sizes to ISO 216

Note that the area of A1 is half that of A0 and so on down the list. Also, the width of any size gives the height of the next smallest size, and the height is twice the width of the next smallest size.

A5 size is made by folding A4 in half, A6 by folding it in half again etc…