More than you need to know about paper sizes

Notebooks, journals and paper often come in A or B sizes, such as A4, A5, and A6, or B4, B5 and B6. But, what are these sizes and why do we measure paper like this?

The history of paper sizes

Australia took its time adopting the paper standards of the world. In 1974 we adopted the A size for paper, but we were one of the last countries to do so. By 1975, Colombia and Kuwait were the last to adopt what is now a well established international standard. Even New Zealand had adopted the paper standard 11 years before we did, in 1963.

The A size of paper was actually based on a German standard from around 1922 known as DIN 476. Interestingly, the French also created a standard that was very similar to the standard we use now, but it was not widely adopted at the time. A French mathematician by the name of Lazare Carnot had his finding published all the way back in 1798 during the French Revolution, showing how significant the history of these sizes is and how they are rooted in mathematics. The international paper sizes standard is known as ISO 216 and was widely adopted by the rest of the world before it became a standard in Australia. The ISO paper standard is used all around the world, except in the United States of Ameria, Canada and parts of Latin America where they use the letter and legal formats. All ISO paper standards are based on the same aspect ratio of the square root of 2. As a result, as the number in the series increases, the size of the paper halves.

The A series

"The A series", it sounds like marketing speak, trying to sell you something you don't need, but its a little more dignified than that. The A series is what the paper standards of the world were based upon. There are 11 sizes within the A series, ranging from A0 to A10. The A series starts with A0 which has an area of exactly 1 meter squared. Like all ISO paper sizes, the A series paper decreases by half for each increment in the series. For example, A1 is half the size of A0, and A5 is half size of A4. The A4 size is the most common paper size in the world, used primarily for copy paper that we put into printers to print the many documents we reference on a daily basis. A5 has become more popular for journals and notebooks due to its more compact size, making it easier to carry around.

The B series

Less common is the B series. The B series also has 11 sizes, ranging from B0 to B10. B0 is 1 meter wide, where A0 is 1 meter squared. As a result, B sizes fall inbetween the A sizes and are often used when the A size is too small and the next a size is too large. As one example, books are often printed in B5 size where A5 would be too small and A4 is too large. Other than books, the B series is also used in the printing industry where the slightly larger size allows for printing multiple A series pages together to minimise paper wastage.

Letter, Legal and Ledger sizes

We can't talk about paper sizes without talking about the crazy sizes our friends in America, Canada and the Philippines have adopted as their standard. These sizes (letter, legal, ledger and others) are based on the imperial measure of inches. Unlike the ISO standard however, there is no logical scaling of sizes, its just what happens to have been set as a standard, and then whatever you want for other sizes. As for why the sizes are the way they are, there appears to not be a lot of documentation. For example, the letter size length is 11 inches, which is explained by the American Forest and Paper Association as being "the average maximum stretch of an experienced vatman's arms", which is very helpful. You may also have heard of the size 'foolscap', which is another way to describe the legal size. Legal pads are of the legal size, measuring the same width as letter (8.5 inches) but 14 inches long rather than 11 inches long for the letter size. There are also interesting variations on these sizes like "legal extra" or "letter extra", which are just that "extra" bit wider and longer. To make things more interesting they also have a "letter plus" size, but not a "legal plus". I'm starting to understand how Apple have decided on their phone sizes.

So, that's definitely more than you will ever need to know about paper sizes. But, now you can hopefully appreciate the logic behind the ISO paper sizes and also wonder why the Amercians insist on adopting strange and unnecessarily complex standards.