A Sizes for Posters or Paper

The simplest way to explain the aspect ratio of A sizes is that two of one size will equate to one of the next size up. For example, 2 x A4 sheets side by side (portrait) will equate to 1 x A3 page and 2 x A3 pages side by side (portrait) will equate to 1 x A2 size.

The larger the size of paper the smaller the number – A10 is the smallest and A0 size is the largest.