Here is a list of paper sizes – see further down for how this is calculated.

Paper Size	Width (mm)	Heigh (mm)
A0	840.9	1189.2
A1	594.6	840.9
A2	420.4	594.6
A3	297.3	420.4
A4	210.2	297.3
A5	148.7	210.2
A6	105.1	148.7
A7	74.3	105.1
A8	52.6	74.3

Zoom

Here are the zoom factors for going from one size to the other. You can also use this to calculated what font size you need if the page is going to be enlarged. For example you would need a 12*141.4%=17 point font if you were going to reduce an A3 page down to A4 and you wanted the font to be 12 point in the final reproduction.

How this all works

To be able to resize from one page size to the other without distorting the image then the aspect ratio of the pages must be the same. The aspect ratio is the ratio of width to height.

To change from one paper size to the next smaller paper sizes you simply cut page in half and rotate:

Looking at the diagram above our restraint on the aspect ratio becomes

But we can also see the y₂ = x₁ and x₂ = 1/2y₁. Putting this into the equation above we have

So that we know that the height must be the width times the square root of two.

A0 has a total area of 1m² = 1×10⁶mm². Therefore we can calculate width and height since we know that the width times the heigth is x₁y₁ and also

so we have

This gives a width for A0 of 840.9mm and a width of 1189.2mm.

The spreadsheet with these figures and positions of text boxes for a three column landscape page is given the the spread sheet paper sizes.