What is the aspect ratio in standard paper formats A0, A1, A2, etc.?

If you also need sizes, then here is the table

1 to the root of 2. Only with this aspect ratio does bending in half maintain proportions: the root from 2 relates to 1 as much as 1 refers to the root from 1 / 2. And one format from another is obtained by bending in half.

All of the listed paper sizes have the same aspect ratio. This aspect ratio is called the "Lichtenberg ratio" and if the short side is taken to be 1, the long side multiplier is equal to the square root of 2 or 1,4142857.

Writing this ratio as a fraction of integers looks like 99 / 70.

A format with a large numerical value is obtained by cutting in half a sheet with a format of a smaller numerical value. For example, from an A0 format sheet, two A1 sheets are obtained. Two sheets of the A1 format are obtained from an A2 sheet, two A2 sheets are obtained from a A3 sheet, etc.

The initial format of the A0 sheet is one square in area. meter. The most popular A4 paper size in area is 1 / 16 of a square meter.