What are the different sizes of paper?
In the UK, most paper sizes fall into the A and B series. Let’s go through what these different sizes of paper are and how to use them.
International standard for paper sizes: A, B and C series.
Paper sizes have evolved since their creation. Geographical factors also have a big impact on different terms, names and sizes for paper.
In the UK, when we pick up a magazine or print off a document, we normally handle A4. This is standardised by ISO 216 and is the same across most of the world.
However, the United States, Canada and many other countries of North/Central America do not use ISO 216. Instead, they use the American National Standards (ANSI) formatting. Here, you’ll find sizes like letter and legal in place of A4 and A5. This can make things trickier for designers, publishers and artists who work internationally.
ISO 216 is characterised by the √2 aspect ratio, used for both the A series and the B series. The scientist Georg Christoph Lichtenberg described this width/length proportion in a 1786 letter addressed to Johann Beckmann, a German antiquarian and physicist.
Essentially, if you cut a √2 rectangle in half (parallel to the shorter side), then the resulting two rectangles will maintain √2 proportions. In paper terms, you can cut an A3 page in half to make two A4s. Half an A4 is an A5 and so on.
However, it was not until 1922 that the first standard was adopted by Porstmann and the German DIN 476. The C series is defined by ISO 269, which is mainly used for envelopes.
Paper sizes in the A series.
The ‘A’ series of paper formats range from A0, which is the largest, to A10, the smallest.
The A0 sheet measures 84.1 x 118.9 cm or 33.1 x 46.8 inches and has a surface area of 0.999 949 m² or almost 1 m², which corresponds to 16 A4 sheets.
As for the A1 paper size, it represents ½ of an A0 sheet and measures 59.4 x 84.1 cm or 594 x 841 mm.
We can clearly see that the size of the A1 format, like that of the other formats, relates closely to the √2 aspect ratio. For example, the A1 format is obtained by halving the length of the A0 paper size and taking the width value of the A0 format as the length. This process will be followed until we get the A10 paper size. In other words, an A1 sheet represents ½ of an A0 sheet, two A2 sheets, four A3 sheets, eight A4 sheets and so on.
If this relationship between the different paper sizes of the series feels confusing, here is a formula that sums it up: length = width x 2 for all A formats.