A UK Guide to Notebook Paper Sizes: A4, A5, B5 and Pocket Compared
Walk into any stationer and the covers get all the attention. The numbers on the back sticker do the real work. Get the size wrong and a beautifully bound notebook will sit on the shelf, too heavy for your bag, too cramped for your handwriting, or too big to open on a train without elbowing the person beside you. The good news is that the main formats are easy to compare once you know what each one is for.
What the Numbers Actually Mean
Two conventions cover almost everything you'll see on a UK shelf: the ISO A series and the ISO B series. Each A size is exactly half the area of the one above it and keeps the same proportions, which is why A5 is simply A4 folded once. The B sizes slot in between, so B5 is smaller than A4 but larger than A5. In millimetres:
- A4 — 210 × 297 mm. The same as a sheet of printer paper.
- B5 (ISO) — 176 × 250 mm. Japanese JIS B5 is 182 × 257 mm.
- A5 — 148 × 210 mm. Half of A4, and the standard diary size.
- A6 — 105 × 148 mm. Half of A5, roughly postcard-sized.
Two warnings before you order anything. First, B5 comes in two versions: ISO B5 and the slightly larger Japanese JIS B5. The difference looks trivial until you buy a cover or a refill made for the other one, so check the listing carefully. Second, a cover adds a centimetre or more in each direction. A thick 200-page A5 is a different object in the hand from a slim 48-page one. The paper size is a starting point, not the whole story.
A4: The Desk Notebook
A4 is the size you reach for when you have a table. Lectures, project notes, mind maps, anything where you want two full pages open side by side: source material on the left, your notes on the right. It lies flat, takes a diagram with labels without forcing you to write at the size of a gnat, and gives generous margins if you like annotating later.
Where it loses is portability. A hardback A4 is not something you write in on a crowded commuter train, and if your handwriting is small you'll be leaving a lot of blank space on every page. A4 earns its keep if most of your writing happens sitting down. If it doesn't, buy something smaller and keep an A4 pad at home for the heavy sessions.
A5: The Everyday All-Rounder
If you only ever own one size, make it A5. Open it and you get roughly an A4 writing area across the spread, but the closed notebook fits a rucksack, a tote, most handbags and the side pocket of a work bag. It sits on a café table with room left for a cup. Diaries, planners and the majority of journals are A5 by default, so covers, refills and inserts are easy to find in the UK and usually affordable.
The caveats are about ruling and thickness. If you write large, 7 mm lines in A5 will feel tight — look for wider ruling, or go dot grid or blank. A fat hardback A5 is heavier than you expect, and a slim one with fewer pages may suit you better if you never fill notebooks anyway.
B5: The Quiet Middle Ground
B5 is what people discover after A5 starts to feel cramped. That extra width is the point. You gain about 28 mm across and 40 mm down compared with A5, which means longer lines and enough room for two columns on one page: tasks down the left, notes down the right. Study notebooks and many Japanese stationery lines use it well.
The trade-offs are practical rather than aesthetic. Fewer UK shops stock B5 covers and inserts than A5, it's heavier to carry, and it won't fit a coat pocket. If your handwriting sits somewhere between tidy small print and a generous scrawl, though, B5 is worth hunting down. Just confirm whether the notebook is ISO or JIS before buying anything to go with it.
Pocket Notebooks: A6 and Smaller
A6 is half of A5 and about the size of a postcard. This is the classic pocket notebook, usually sold in packs, often with a stapled spine and a card cover. One thought per page. A shopping list, a phone number, a book title, a line you don't want to lose between the car park and the kitchen. They live in a jacket pocket or a back jeans pocket, though a softcover will bend and eventually fray at the corners.
A6 versus A7
A7 is 74 × 105 mm, half of A6 again and barely larger than a bank card. Fine for a list, useless for minutes. If you plan to write more than a few lines at a time, treat A6 as the sensible floor and don't go smaller.
Size Against Use: Journaling, Notes and the Commute
Journaling
A5 is the safe default. Choose B5 if you stick things in — receipts, tickets, a photograph, a strip of washi tape — because the extra width stops the page feeling crowded. Choose A6 only if you write a few lines a day and know you'll carry it. There's no shame in a small journal you finish rather than a grand one you abandon in February.
Note-taking
At a desk, A4 or B5. Around a meeting table where everyone needs elbow room, A5. If you're capturing one action per line to type up later, an A6 in your pocket will do the job and you'll actually have it with you. Ring-bound notebooks lie flat and are easy to rearrange, but the wire can dig into your hand; stitched lay-flat bindings are kinder if you write on your knee.
The commute
Measure your bag before you buy. A5 is the natural commuter size; A6 is the one that survives in a coat pocket. Writing while standing is its own skill, and a hardcover gives you a firm surface where a softcover won't. Many people end up with two: A5 for the desk, A6 for the pocket, and an A4 pad at home for anything sprawling.
How to Choose Without Overthinking It
- Write a couple of lines on scrap paper and measure the space you naturally leave. Under about 6 mm, skip standard ruled paper and pick dot grid or blank instead.
- Decide where the notebook will live. That tells you more than what you plan to write in it.
- Buy one A5 and one A6 and use
Photo: milad2fan / Pixabay
