
There are brands that have their own measurements, I'm thinking of Notem for example, its notebooks don't fall into any of these categories in terms of precision but these are the typical measurements:
A4 format:
Dimensions: 210 x 297 mm.
It is one of the most common and standard formats for notebooks and notepads, the ones used in school, so to speak.
It's ideal for taking notes in class, writing documents, or making detailed drawings because there's plenty of space.
A5 format:
Dimensions: 148 x 210 mm.
It's smaller than A4 size but still large enough to hold detailed notes. It's the typical size of classic planners and is the ideal solution for writing and taking notes because it offers enough space for plans, notes, and lists. It's also very handy, making it perfect as a diary or bullet journal.
Format: A6:
Size: 105mm × 148mm
It's the classic pocket notebook, small and compact, ideal for quick notes, shopping lists, reminders, the one you always have with you because it fits in a pocket or comfortably in a bag.
B5 format (mainly used in Japan and some other Asian countries.):
Dimensions: 176 x 250 mm
It's a little smaller than the A4.
It is suitable for those who need more space for writing, drawing or taking detailed notes, but still want a fairly compact format.
B6 format (typical of Japanese products):
Dimensions: 125 x 176 mm
It is larger than the B7 but smaller than the B5.
It is useful for those who want a notebook smaller than the A5 format but do not want to sacrifice too much space for writing and would feel too cramped with an A6 notebook.
B7 format (still widely used in Asia)
Dimensions: 88 x 125 mm .
It is a very compact and small size, ideal for those who need to take notes on the go or for jotting down short notes.
It can be convenient for those who want a pocket-sized notebook to carry everywhere.
Choose the notebook size based on your specific needs. If you want to always have it with you, you might prefer a smaller size like A6. If you need more space for detailed writing, A4 might be more suitable. The most popular is the A5 model, which is the perfect middle ground.
Also consider the paper type and internal layout of the notebook based on how you intend to use it.





