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A1, A2, A3, A4 learn about paper sizes, if you’d like to know more

10th March 2010


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Everyone uses standard paper size terms but do you they understand what they mean and why?

International Standard (ISO 216) specifies paper sizes used in most countries in the world today (except for the US and Canada which uses its own sizing standard) and the development of these paper size ratios can be dated back to the Eighteenth Century. Before the adoption of this standard, paper sizes did not fit into any formal system and did not work with metric units and it wasn’t until 1975 when so many countries were using this paper sizing system that the International Standard was formalised.

There are a lot of mathematical fomulas behind the workings of A, B and C paper sizes but the underlying feature is that any successive paper size (eg. A1, A2, A3, A4) measurement is determined by halving the dimensions of the preceding one. For example the most commonly used paper size is A4 (297mm x 210mm) and the next paper size is A5 (210mm x 148.5mm) which is equal to half of the A4 dimensions.

The main uses of A, B and C paper sizes is their application to a particular print project. For example C paper sizes are solely used for the manufacture of envelopes and are sized in a way that would allow an A4 piece of paper to fit nicely into a C4 envelope. B sized papers are larger than A sizes and are generally used for oversized projects such as posters and folders, and allow for multiple page documents to be printed on fewer sheets and more economically.

Commonly printed items such as a postcard (A6), flyer (A5) or newsletter (A4) will be printed at a standard size, it is at the special request of a customer to create something with a bespoke size that would change this. Therefore a request to quote for a postcard would be based on A6 size (148.5mm x 105mm):

  • A0 (841mm x 1189mm)
  • A1 (594mm x 841mm)
  • A2 (420mm x 594mm)
  • A3 (297mm x 420mm)
  • A4 (210mm x 297mm)
  • A5 (148.5 x 210mm)
  • A6 (105mm x 148.5mm)
  • A7 (74mm x 105mm)
  • A8 (52mm x 74mm)
  • A9 (37mm x 52mm)
  • A10 (26mm x 37mm)

Click on the images below to see paper size dimensions in greater detail.