Paper Sizes – A vs B

A series vs B series Paper size

Have you ever wondered what the numbers on the cover of a box of printer paper meant? Have you ever wondered what the difference between B4 and A4 is, and why there are so many numbers on the box that is so confusing? Don’t worry, we’re here to help you decode and understand the world of paper sizes.

A series

During the 1920s, the size of the paper was first introduced in Germany and quickly spread throughout Europe and the world. It was codified by the International Organization for Standardization in the 1970s after becoming widely used around the world.The largest size, A0, is 84.1 cm 118.9 cm (approximately 33.1″ 46.8″). Each smaller size is made by cutting the next largest size in half, resulting in size with the same proportions as the previous one but half the surface area.

When you cut a piece of paper in half, you usually get two pieces with completely different proportions than the original. However, in this case, it works because of an interesting mathematical phenomenon: when a sheet of paper with a 1:2 aspect ratio. Let us look at two of the most popular A4-sized papers in the world.


A4 is by far the most widely used paper size today. The A4 page is the industry standard for office document sizes, measuring 210 x 297mm.

A4 paper is available in a variety of weights ranging from 75gsm2 to 300gsm2, as well as a variety of types such as index paper, cover paper, and text paper, each with its own thickness, strength, and feel.

In addition to printing in A4 formats, most modern printers can also print on smaller media such as A5 and A6.

An A4-sized printer should suffice for the majority of day-to-day printing tasks.


A3 is the second most popular paper size in the average office. A3 paper is exactly twice the size of A4 paper, measuring 297mm x 420mm. A3 printers have a number of advantages over A4 printers, including faster print engines, larger toner cartridges, and longer duty cycles, to name a few.

Another benefit of A3 printers is that they can print in smaller sizes such as A4, A5, and A6.

B series

The B paper sizes follow the same principles as the A sizes, with a 1:2 aspect ratio and each size having half the area of the next largest. The difference is that B sizes are in the middle of the A sizes, allowing for greater granularity. The B5 size, for example, is halfway between A4 and A5.

Unfortunately, B sizes become a little more complicated. The dimensions of B sizes are defined differently in Japan than in the rest of the world, unlike A sizes, which are the same everywhere. Let’s look at two of the most popular ones.


A B4 sheet of paper is 250 x 353 mm in size. It can be cut in half to make two B5 sheets of paper.


A B3 sheet of paper is 353 x 500 mm in size. It can be cut in half to make two B4 sheets of paper.

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