Notebook Sizes Explained: A4, A5, A6, B5 & B6 Compared

Looking for the right notebook size?

A4, A5, B6... with so many options available, choosing the right notebook can be surprisingly difficult. In this guide, we explain the most common notebook sizes and help you find the format that best suits your writing style — whether you enjoy journaling, making lists, planning your days or sketching ideas on paper.

Questions about notebook sizes are among the most common questions we receive at Het Noteerhuis.

Notebooks are available in a variety of formats. Below, we explain the most common sizes and compare them side by side so you can clearly see the differences.

Across Europe, notebook sizes are usually based on the A-series and B-series paper standards. In North America, formats such as Letter and Legal are more common.

The A-Series Standard

The paper in your printer is most likely A4 size. An A4 sheet measures 21 × 29.7 cm (8.27 × 11.69 inches). A4 is derived from the larger A3 format and is exactly half its size. This principle continues all the way up to A0, which measures 84.1 × 118.9 cm and has a surface area of one square metre.

If you fold an A0 sheet in half along its longest side, you get two A1 sheets. Fold an A1 in half and you get two A2 sheets, and so on. The proportions remain identical throughout the entire A-series.

An A4 notebook is therefore twice the size of an A5 notebook. A5 is one of the most popular notebook formats thanks to its balance between portability and writing space. An A6 notebook is half the size of an A5 and is often referred to as a pocket notebook.

The aspect ratio of the A-series is approximately 1:1.414, which is what allows the proportions to remain consistent when the size changes.

Below, you can compare A4, A5 and A6 notebook sizes side by side.

Here you can see A4, A5 and A6 in realistic proportions. A helpful visual comparison when choosing the size that suits your writing habits.

Tip: have a look at all of our A4 notebooks, choose your ideal A5, choose your own fun-sized A6 (pocket).

The B-Series Standard

B-series notebook sizes are less common than A-series sizes but are still widely used by certain notebook brands. At Het Noteerhuis, for example, several notebooks are available in B5 and B6 formats.

The B-series was developed to fill the gaps between A-series sizes. A B6 notebook, for example, sits neatly between A6 and A5.

Like the A-series, the B-series maintains the same aspect ratio of approximately 1:1.414. The notebooks are simply slightly larger than their A-series counterparts while preserving the same proportions.

If you find A6 too small and A5 slightly too large, B6 is often an excellent compromise.

Tip: check out our B5 notebooks, choose your favourite B6.

Notebook Size Dimensions

Looking for the exact measurements? The table below compares the most common notebook sizes.

Table 1 – Common A-series and B-series notebook dimensions.

Did you know that the choice between A5 and B6 is often the difference between maximum portability and maximum writing space?

Ready to Choose Your Ideal Notebook Size?

Explore our collections of A4 notebooks, A5 notebooks and B6 notebooks — carefully selected for everyday writing, planning and reflection.

Also worth reading: our guide on how to choose a notebook for fountain pens.