Open A5 and B5 notebooks compared on a table

A5 vs B5: Which Notebook Size Suits Your Desk?

A5 measures 148 × 210 mm and ISO B5 measures 176 × 250 mm, so B5 is 28 mm wider and 40 mm taller. Choose A5 if your notebook travels or shares a small desk. Choose B5 if the notebook is where the real work happens: long notes, diagrams, study spreads. The catch is that “B5” on a product page does not always mean the same thing, and we cover that below.

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TL;DR

  • A5 is 148 × 210 mm; ISO B5 is 176 × 250 mm. B5 gives roughly 42% more page area, with the same proportions.
  • A5 suits bags, meetings, daily logs and compact desks. B5 suits study, mind maps, two-column notes and long-form journaling.
  • “B5” can mean ISO (176 × 250 mm), JIS (182 × 257 mm) or Semi-B5 (around 179 × 252 mm). Check the listed dimensions, not the label.
  • A5 halves cleanly from A4 for printing. B5 does not, so printing needs scaling of about 84% or 119%.
  • Size says nothing about paper weight, ruling or binding. Compare those separately.

Table of Contents

The exact sizes, side by side

Both sizes come from ISO 216. Microsoft’s paper-size documentation lists A5 at 148 × 210 mm, and PaperSizes.guide gives ISO B5 as 176 × 250 mm.

A5 ISO B5
Millimetres 148 × 210 176 × 250
Inches (approx.) 5.8 × 8.3 6.9 × 9.8
Page area (approx.) 31,080 mm² 44,000 mm²
Relation to A4 Exactly half Between A5 and A4, not a clean fraction
Best for Carrying, short notes, light layouts Desk work, study, diagrams

The same comparison puts B5 at roughly 42% more surface area than A5. Both formats share the same 1:√2 proportion, so B5 is not squarer or wider in shape. It is simply a larger version of the same page.

In practice, 28 mm of extra width is easy to feel. It is the difference between a page that holds one comfortable column of handwriting and one that holds a column plus a margin of annotations.

The B5 trap: ISO, JIS and Semi-B5

A5 is the same everywhere. B5 is not. The ISO version is 176 × 250 mm, but the Japanese JIS B5 is 182 × 257 mm, and notebooks sold as Semi-B5 sit around 179 × 252 mm, according to PaperSizes.guide. A Japanese stationery guide lists the standard B5 notebook at 179 × 252 mm.

That gap of a few millimetres matters if you are buying:

  • a notebook cover or sleeve
  • a refill or insert for a ring binder
  • a desk organiser with a notebook slot
  • a desk mat you want the notebook to sit neatly on

One UK notebook retailer’s chart carries a reminder to check individual products for exact measurements, which is good advice. Also compare the external size of the finished notebook, not just the paper size. Covers, rings and lay-flat bindings all add width.

A5 or B5 for journaling and planning

Neither is universally better. A 2024 comparison from a planner writer found A5 works well for minimalist layouts, portability and everyday carry. B5 earns its space when you combine work and personal planning, use two columns, draw, or want more white space on the page.

A simple rule that holds up for most UK home offices:

  1. Daily log, to-do lists, meeting notes: A5. One page a day fits without feeling cramped, and the book slips into a bag.
  2. Weekly spreads with habit trackers: either. A5 is tidy if you keep trackers small; B5 is easier if you like generous boxes.
  3. Long-form journaling or free writing: B5 means fewer page turns and a more relaxed line length.
  4. Mind maps, sketch notes, collage: B5.

The question to ask is not which is better but where the notebook lives. If it travels, A5. If it stays on the desk, B5 deserves a look.

A5 or B5 for study

For students, the page is a working surface. The Japanese student notebook tradition leans on B5 for good reason: it is large enough for detailed notes and diagrams without reaching A4. Kokuyo’s own guide makes a similar point, noting that Semi-B5 gives a wider writing area while using less desk than A4 or Letter.

If you take lecture notes in B5 and then want to turn them into revision material, a tool that converts slides and notes into structured study notes can save retyping. A larger page helps at the first stage: you can keep the lecturer’s diagram and your own commentary side by side.

A5 still makes sense for students who carry a notebook between lectures, the library and the commute, or who use it only for definitions, formulae and quick reminders. Many students end up with both: B5 for the desk, A5 for the bag.

What about the desk itself?

This is where a minimalist workspace changes the answer. A5 is usually the safer default when the notebook sits beside a laptop, lamp or desk mat, because it occupies less surface and keeps the desk visually quiet. B5 is the better choice when the notebook is the main work surface.

A rough layout check for a typical setup:

  • Laptop plus notebook on a compact desk: A5 leaves room for a mouse, a pen and a lamp without crowding.
  • Notebook as the primary surface, laptop closed or off to the side: B5 sits well on a desk mat and lets you rest your forearm without the page shifting.
  • Shared dining table or fold-down desk: A5, so you can clear it quickly.

If you want to plan the whole surface, our guide to desk mat sizes explains how to measure before you buy, and our minimalist desk setup ideas show how much to leave empty.

Printing and templates

If you print your own planner pages or inserts, A5 has a practical edge. Two A5 pages fit on one A4 sheet, which suits ordinary UK printers and folded booklets. B5 does not halve cleanly from A4, so B5 documents may need a larger sheet or a print-shop workflow with trimming.

Scaling between the two is straightforward. Cambridge’s scaling guide lists A5 at 148 × 210 mm and B5 at 176 × 250 mm. Reducing B5 to A5 means about 84%, and enlarging A5 to B5 means about 119%. Printer margins and bleed can still change the usable area, so do not assume “fit to page” keeps your layout intact. Print one test page first.

A5 and B5 dimensions with print scaling percentages

Common mix-ups

Is 8.5 × 11 inches the same as A5? No. That is US Letter. Microsoft lists Letter at 8.5 × 11 in and A5 at 148 × 210 mm. In the UK, A4 (210 × 297 mm) is the everyday office size, and A5 is its exact half.

Does size decide quality? No. Size does not determine ruling, page count, paper weight, binding or capacity. Check each separately. Fountain pen and ink users in particular should look at paper weight and finish before size.

Will any refill fit? Not necessarily. Kokuyo’s guide notes a 26-hole Japanese B5 system and a 20-hole Japanese A5 system, and Western ring formats may not be interchangeable with them. Check the hole pattern before buying refills.

Our view: why we lean towards A5 on a calm desk

We design around a quiet workspace, and that shapes how we think about notebook size. A desk reads as calm when there is visible space between objects. An A5 notebook, a lamp and a mat leave that space; a B5 notebook sitting beside a laptop often takes it away.

That is not a rule against B5. If you write for hours by hand, or you sketch and diagram, the larger page is worth the footprint, and we would rather you were comfortable than tidy on paper only. Our suggestion is to decide by use: A5 for the notebook that goes with you, B5 for the one that stays and does the heavy lifting.

Whatever you choose, measure the finished notebook against the space you actually have. Our A5 vs A6 guide applies the same logic one size down.

— Joel

A notebook that suits a considered desk

If you are leaning towards a notebook that feels as good as it looks, our Handmade Leather Notebook has a cowhide cover and costs 38 GBP. Check the dimensions on the product page against your desk, as we suggest above. Pair it with a Natural Cork Desk Mat from 19 GBP or a Cork & Vegan Leather Desk Mat from 39 GBP to give it a defined spot. Shipping in the UK is free, and returns are free within 30 days.

How to choose in two minutes

  1. Decide where it lives. Mostly in a bag: A5. Mostly on a desk: B5 is worth considering.
  2. Decide what goes on the page. Lists and short notes: A5. Diagrams, two columns, long writing: B5.
  3. Measure your desk. Lay a sheet of paper cut to 176 × 250 mm beside your laptop. If it feels crowded, choose A5.
  4. Read the listing. Confirm whether B5 means ISO, JIS or Semi-B5, and check the external dimensions.
  5. Check the paper. Weight, ruling and binding matter as much as the size.

FAQ

Are B5 and A5 the same?

No. A5 is 148 × 210 mm and ISO B5 is 176 × 250 mm, so B5 is 28 mm wider and 40 mm taller. B5 offers about 42% more page area, while the proportions are the same.

Is A5 or B5 better for journaling?

It depends on how you use the journal. A5 is better for portability, concise daily logs and minimalist layouts. B5 is better for long-form writing, two-column spreads, drawing and a roomier page.

Is B5 bigger than A5 in every country?

B5 is always bigger than A5, but its exact size varies. ISO B5 is 176 × 250 mm, JIS B5 is 182 ×257 mm and some Japanese notebooks are Semi-B5. Check the stated dimensions before buying covers or refills.

Can I print a B5 document on A5 paper?

Yes, by scaling it to about 84%. Going the other way, A5 to B5, needs about 119%. Margins and bleed affect the final result, so test one page before printing a batch.

Sources

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