A Paper Sizes Explained

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.

ISO 216 specifies the international standard of paper sizes which is used in most countries worldwide apart from Mexico, Dominican Republic, USA and Canada.

Paper Size Dimensions:

When purchasing notice boards, if the sizes are quoted in 'A' sizes then this is the visible area for the poster and the frame width will need to be added to all four sides to give the overall size.

If you require a 27 x 40 movie poster size, please contact us for more information. We are specialists in printing posters with A3 A4 being a popular choice.

The majority of our printed posters and graphics are available in A series sizes, and in the following additional standard dimensions:

• 20 x 30in [508 x 762mm]
• 30 x 40in [762 x 1016mm]
• 40 x 60in [1016mm x 1524mm]

In addition to A series sizes and other standard dimensions, it is also possible to use the B series paper sizes.

The B series paper sizes are defined in ISO 216 in the following way:

“The B series paper sizes were created in order to provide paper sizes that weren't covered by the A series, but also use an aspect ratio of 1:root2. B sizes are defined as size B(n) being the geometric mean of size A(n) and size A(n-1). The Geometric Means of 2 numbers being the square root of the product of the two numbers. This system gives a useful property for enlarging and reducing documents in that the enlargement from A(n) to B(n) is the same as that from B(n) to A(n-1).”

You’ll find that, similar to the A series paper sizes, the standard lengths and widths are rounded to the nearest millimetre.