Paper
The best B5 notebooks for fountain pens
Bigger than A5, smaller than A4, and the size most people should be writing longhand on. Almost nobody knows it exists.
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B5 is a size most Western buyers have never deliberately chosen, because Western stationery is sold in A4 and A5 and stops there. In Japan it is the standard student notebook, and once you have written a few pages on one the reason becomes obvious: it is the largest sheet you can still write across comfortably without moving your forearm.
How the ISO sizes work
The A series starts at A0, one square meter, and each subsequent size halves the previous one along its longer side. A4 is half A3, A5 is half A4, and every size shares the same proportions.
The B series sits between the A sizes. B5 is larger than A5 and smaller than A4, which is exactly the gap where longhand is most comfortable: wide enough for a full line of thought, short enough that your hand does not travel far.
| Size | Roughly | Best for |
|---|---|---|
| A6 | Lists, a carried notebook | |
| B6 | Slightly larger than pocket | A daily log, a travel journal |
| A5 | Half a sheet of letter paper | The default journal size |
| B5 | Between A5 and A4 | Longhand at a desk, study notes |
| A4 | A sheet of letter paper | Drafting, diagrams, printed forms |
Quick picks
Ranked for the beginner buying their first setup. Every pick names who it is wrong for.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | No image Kokuyo Campus B5, ruled The Japanese school notebook, in B5, at a price that makes writing a hundred pages feel free. | Volume writing on a budget | Check price on Amazon #ad No live price right now. How this is funded |
| 2 | No image Stalogy 365 Days Notebook B6 A thin-paper daily notebook with a full year of dated grid pages in a book you can still carry. | One book for a whole year | Check price on Amazon #ad No live price right now. How this is funded |
| 3 | No image Maruman Mnemosyne A5, ruled Twin-wire bound, 80 g/m2 acid-free Japanese paper, perforated to tear out cleanly. | Meeting notes and work you tear out | Check price on Amazon #ad No live price right now. How this is funded |
1. Volume writing on a budget
Kokuyo Campus B5, ruled
The Japanese school notebook, in B5, at a price that makes writing a hundred pages feel free.
#ad No live price right now. How this is funded
B5 is the size worth knowing about. It is bigger than A5 and smaller than A4, which turns out to be the right size for a page of longhand that you can still fit on a desk beside a laptop.
Kokuyo does not publish a weight for this notebook. What it does publish is the ruling, the sheet count and the fact that it lies flat.
At this price it is the notebook to use for drafts, practice and anything you would otherwise not write down at all.
| Size and ruling | B5, 6 mm ruledSource: Kokuyo Campus B5 (retail listing, read 2026-09-01) |
|---|---|
| Extent | 100 sheetsSource: Kokuyo Campus B5 (retail listing, read 2026-09-01) |
| Paper weight | Not published |
| Binding | Stitched, lies flat when openedSource: Kokuyo Campus B5 (retail listing, read 2026-09-01) |
What it does well
- Very cheap per page
- B5 is a genuinely useful longhand size
- Lies flat
What it does not
- No published paper weight
- Soft cover with no protection
- Ruling is tighter than most Western notebooks
Skip this if you write with a broad, wet nib — thin school paper is the worst case for show-through.
2. One book for a whole year
Stalogy 365 Days Notebook B6
A thin-paper daily notebook with a full year of dated grid pages in a book you can still carry.
#ad No live price right now. How this is funded
The idea is a single book for a year: thin paper, high page count, and a date grid printed at the top of every page so you do not have to write one.
Stalogy does not publish a weight, and the buyer feedback on its own listing is openly divided on bleed-through — some inks are fine, some are not. That division is what thin paper looks like when it is well made but still thin.
Ghosting is guaranteed. Whether it bothers you is a matter of taste, and some people like it.
| Format | B6, 365 Days NotebookSource: Stalogy 365 Days Note B6 (retail listing, read 2026-09-01) |
|---|---|
| Paper weight | Not published |
| Ruling | Grid, with date and time markers printed on each pageSource: Stalogy 365 Days Notebook, B6 slim, squared (retail listing, read 2026-09-01) |
| Also available | A5, A6 and B5 in the same formatSource: Stalogy 365 Days Notebook, A5 (retail listing, read 2026-09-01) |
What it does well
- A full year in one carryable book
- Date grid printed on every page
- Several sizes in the same format
What it does not
- No published paper weight
- Bleed-through reports are genuinely mixed
- Ghosting is unavoidable at this thickness
Skip this if show-through bothers you, or if you want to use a broad nib every day.
3. Meeting notes and work you tear out
Maruman Mnemosyne A5, ruled
Twin-wire bound, 80 g/m2 acid-free Japanese paper, perforated to tear out cleanly.
#ad No live price right now. How this is funded
80 g/m2 is the lower end of what a fountain pen is comfortable on, and Maruman gets away with it because Japanese paper of the same weight is denser and more tightly sized than European office stock. That is why an 80 gsm Japanese notebook can outperform a 90 gsm cheap one.
The spiral binding is the practical part: it folds fully back on itself, so it works on a train or on a knee.
This is a working notebook, not a keepsake. The perforation exists because you are meant to tear pages out.
| Paper weight | 80 g/m2, acid-freeSource: Maruman Mnemosyne A5 (retail listing, read 2026-09-01) |
|---|---|
| Extent | 80 sheets (160 pages), 7 mm college ruledSource: Maruman Mnemosyne A5 (retail listing, read 2026-09-01) |
| Maker's claim | Resists ink bleed-through with minimal ghostingThe maker's own wording on its listing.Source: Maruman Mnemosyne A5 (retail listing, read 2026-09-01) |
| Binding | Twin-wire spiralSource: Maruman Mnemosyne A5 (retail listing, read 2026-09-01) |
What it does well
- Published weight and an explicit bleed claim from the maker
- Folds completely flat and completely back
- Perforated for clean tear-out
What it does not
- Wire binding is bulky in a bag
- 80 gsm is the floor for a wet nib
- Not a book you would keep on a shelf
Skip this if you want a permanent journal — a spiral pad is a working surface that sheds pages by design.
Why B5 suits fountain pens specifically
Two reasons, and the second is the interesting one. A wider page means fewer line breaks, and fewer line breaks mean fewer places where the nib stops, changes direction and deposits a blob of ink. Long uninterrupted strokes are where a fountain pen is at its best.
The other is that most B5 notebooks in circulation are Japanese, and Japanese paper at a given weight is denser and better sized than European stock of the same figure. The size and the paper tradition travel together.
The catch
B5 does not fit standard Western folders, sleeves or bags designed around A4. If your workflow involves filing pages, check that first — a size nothing else fits is a size you stop using.
Availability is the other constraint. Outside Japanese stationery ranges the choice is thin, which is why two of the picks above are the closest useful neighbors rather than B5 itself.
Questions people actually ask
What size is a B5 notebook?
B5 sits between A5 and A4 in the ISO 216 system. It is the standard Japanese student notebook size and is noticeably wider than A5 without reaching A4.
Is B5 better than A5 for writing?
For longhand at a desk, usually yes — a wider page means fewer line breaks and longer uninterrupted strokes, which is where a fountain pen performs best. A5 remains better for a carried journal.
Where can I buy B5 notebooks?
Mostly from Japanese stationery ranges — Kokuyo, Maruman and Stalogy all make them. Western stationery is built around A4 and A5, so the choice outside Japanese brands is thin.
Does B5 paper fit in A4 folders?
No. B5 is a different series and does not fit A-series folders, sleeves or binders. If you file your pages, check compatibility before committing to the size.