Paper Sizes - The Ultimate Guide.

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.

This series of paper sizes has been extended with formats larger than the A0 format, especially for printing purposes. They are 2A0, 4A0 etc. and are respectively twice and four times larger than A0, but always stick to the same proportions.

Paper sizes in the B series.

The ‘B’ series is widely used in printing to accommodate for both paper size and printing press size. B sheets are often used to print two A sheets at once. One B3 covers two A4 and one B2 has room for four A4.

In the same way as the A series, the paper sizes of the B series are based on the B0 format whose width and length are, by definition, 1m and √2m respectively and whose length/width ratio is therefore also √2.

The areas of the B series have a factor of √2 with the areas of the A series. This format allows widening the margins to integrate a sheet from the A series and of the same number.

Paper sizes in the C series.

The paper sizes of the C series are calculated as being the geometric mean of the areas of An and B sheets of the same number.  The series is mainly used for envelopes and is designed to contain corresponding A/B sheets without the need to fold them.  

For example, a brochure in A4 format fits perfectly in a C4 envelope. Likewise, an A5 sheet fit perfectly in a C5 envelope, as would a folded piece of A4.

The various uses of paper sizes (A series).

The A series, the most prominent paper sizes series, consists of ten subgroups which, as we have seen, range from the A0 format, the largest format on the scale, to the A10, the smallest. Let’s study the different uses of each format.

Large paper sizes: A1 and A0.

A0 paper size or the A1 paper size are almost exclusively available in reprography shops or graphic centres and are generally used for technical drawing. 

This is especially the case for the construction and architecture sectors, because the proportions of the projects can be expected to obtain an accurate rendering. They are also used in the advertising and communication sector because the dimensions of a poster in A0 or A1 format offer a good visibility for the design of promotional materials.

Other super large sizes are available such as 2A0 and 4A0, but these are not formerly defined by ISO 216. The 2A0 paper size measures: 1682 mm x 1189 mm whereas the 4A0 paper size measures: 2378 mm x 1682 mm.

Intermediate paper sizes: A3, A4 and A5.

A3 format is used for the creation of prints or posters and since it is twice the size of an A4 format, it is also used as a visual medium for meetings and presenting ideas. 

The surface of the A5 paper size is half the size of an A4 format and is popular for graphic design because it can be found, for example, in the creation of promotional leaflets, brochures and booklets.

The A4 format is the most commonly used. Whether in a personal or professional setting, we are all familiar with this standard paper size. The A4 sheets are generally sold per 500-unit strip. The A4 paper size is used in many sectors, particularly:

• magazines

• small posters

• menus 

• calendars

The A5 format is used in the publishing and stationery sectors: it can be found on our shelves in books, diaries, notebooks and greeting cards.

Small paper sizes: A6 to A10.

Within the standard paper sizes, there is a range of smaller sizes. 

The A6 paper size is the standard reference when it comes to the printing or editing of photographs. It is also the format used for postcards. The A7 paper size is popular in the advertising and communication sectors as it is often used to design small leaflets, flyers and stickers. 

The A8 paper size is commonly used for business cards, while the A9 paper size is usually used for labels. Although their dimensions prevent you from including a lot of information, there is a lot of graphic design work that goes into these small paper sizes. 

Finally, the A10 paper size is used for coupons, tickets or stamps and is the smallest of paper sizes.

What are the best paper sizes for printing? 

Before printing off your designs, regardless of their size, it is essential to get an idea of the rendering of your print. To do this, you’ll need to consider the desired printing format but also the grammage of the paper. 

It is this data, among others, that will determine the layout and DTP (desktop publishing) work. Not only does your design have to match what you have imagined, but you will also have to create high-quality prepress files. 

These are generally high-resolution PDF files. For example, when printing a poster in A0 format, make sure that the image is 841 x 1189 mm in 150 dpi (dots per inch) or 300 ppi (pixels per inch). It is also important to add a 3 mm bleed margin to your images. This is located around the perimeter of your document and is intended to be removed after printing, thus avoiding cutting directly into the design.

To make these adjustments and create your designs, you can use a DTP software such as InDesign, which has many features both in terms of the different technical aspects and a wealth of creative possibilities. For example, it will allow you to easily add bleed margins to your designs to obtain printed products exactly as you imagined them.

Paper sizes: frequently asked questions. 

What are the different sizes of paper?

In the UK, different paper sizes are standardised by ISO 216. These include the A, B and C series, which generally follow size 0 to 10. 

• The A series is used for general printing purposes.

• The B series is used to print multiple A sheets at once.

• The C series is generally used for envelopes. 

Which is bigger: A2 or A3?

A2 is twice the size of A3. A1, in turn, is twice the size of A2. When it comes to paper sizes, each number represents twice the size of the number following it sequentially.

What size is A5?

A5 paper is 148 x 210 mm or 5.8 x 8.3 inches. A5 corresponds to half the size of A4, one quarter of A3 and twice the size of A6. It is the size of a standard greetings card.

Learn more about paper sizes and graphic design.

• A1 paper size
• A2 paper size
• A3 paper size
• A4 paper size