Side by side comparison of an 8x10 inches print and an A4 paper oster

What is the difference between A4 and Letter? Paper sizes explained.

Depending on where you live in the world, standard paper sizes can vary widely. What is A4? Or Letter? Are those measurements in inches or centimeters? 

This sometimes makes it a little bit complicated when buying prints as there are so many different formats. In this article, we will try to understand the main types of formats and sizes so that you can choose the perfect size of poster for your home or office decor.

What are the main systems of paper sizes?

Nowadays, there are two main systems co-existing: the North American system and the International system.

The North American paper size system

One word of warning before we delve into the intricacies of the North American system: it is complicated, mostly because it has evolved organically.

Loose paper sizes

As its name implies, the North American system is used mainly in the USA and Canada. It is based on traditional paper formats, the origins of which are not always well documented. It is mainly characterized by arbitrary aspect ratios.

The most common formats are Government Letter (8x10 in),  Letter (8.5x11 in), Legal (8.5x14 in) and Tabloid (11x17 in).

north america art prints and poster paper sizes

Some of these formats have been standardized in 1995 by the American National Standard Institute and are used with the ANSI abbreviation.

The Letter format is used mainly for academic and business documents and is probably the standard print size of your personal printer if you live in North America. The Legal format is used for legal pads and the Tabloid or Ledger format is used for of small newspapers.

Some of the formats used in art prints derive from those original formats. For example, 16x20 in is the same aspect ratio as Government Letter but with the sides twice as long.

Architectural paper sizes

Aside from these standard print sizes, there is a wide range of different formats for prints. One set comes from the architectural/engineering industry and is abbreviated ARCH. 

The most widely used are the ARCH B, ARCH C and ARCH D sizes, respectively 12x18 in, 18x24 in and 24x36 in. These are the main print sizes that we offer to our North American customers.

Photographic paper sizes

A third range of formats is used in arts and photography. The aspect ratios are based on camera shutters or art pads formats. The most widely used for medium-sized prints is the 11R format, which measures 11x14 in.


Visual comparison of North America poster sizes in inches


The International paper size system

By comparison, the International system is a lot simpler as the different formats are calculated mathematically based on one standard reference. As its name implies, this system is used everywhere in the world except for North America.

There are 3 ranges of sizes. The most common one is the A range, which is used for printing, from letters and business documents to posters.

The second range is slightly larger, called B and used for specific printing purposes, such as books or passports.

The third range, C, is only used for envelopes. It was created to fit around A formats with a little to spare so that they could be mailed easily.


The B range again fits C formats so you could use a B4 envelope to mail an A4 print inserted into a C4 envelope... aren't mathematics wonderful?

Calculations aside, we at French Vintage Prints use these properties when mailing gift-wrapped antique prints: the A4 prints are packaged into C4 gift envelopes, which fit perfectly into a B4 mailer.

The A range is based on a reference which has a surface of 1 square meter and an aspect ratio governed by the square root of 2. It is called A0 and measures 118.9×84.1 cm (46.8x33.1 in).

All the other sizes in the A range are calculated by folding the previous size in two along its longer side. You can thus fit two A1 pages on an A0 page and so on.

While the international paper sizes are usually defined in millimeters, we find it easier to refer to them in centimeters as this is the unit which is more easily visualized and used in daily life.

Most commonly used international paper sizes used for art prints

The most widely used format for daily use is A4. If you live somewhere else than North America, your home printer is most likely an A4 printer.


How to compare North American and International paper sizes

If you live in North America, you surely wonder how an A4 relates to a Letter size. If you live elsewhere, you might have wondered about the same thing in reverse.

An A4 measures 21 x 29.7 cm, which is precisely 8 1/4×11 17/24 inches (1 inch=2.54 cm in case you want to check the conversions). This means that a Letter format is slightly shorter than an A4 but slightly wider.


 At French Vintage Prints, we usually offer a choice between A4 and 8x10 inches prints for our smaller formats. Here they are side by side so that you can compare. Again, an A4 is  21x29.7 cm or 8 1/4×11 17/24 inches, while an 8x10" print measures 20.3x25.4 cm. The A4 is thus more of a "portrait" format, while the 8x10 inches is a little more squarish.


Comparison between an 8 x 10 inches print and an A4 poster


As most of our vintage originals are based on International paper sizes, the aspect ratios of the original illustrations are closer to those of A or B international formats. This is why there may be different widths of margins when adapting them to North American poster formats. 


north america art print sizes comparison


At French Vintage Prints, we offer both International and North America poster sizes so that you can easily find frames that fit in your local stores.

And if you are interested to delve deeper into the intricacies of paper sizes, don't hesitate to consult the in-depth Wikipedia article on the subject.


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