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Notebook Sizes Explained: A4 to A7, B5, B6 & More
Picking a notebook size sounds trivial until you've bought the wrong one — an A4 too bulky to carry, or a pocket size too cramped to write in. Get it right and the notebook gets used; get it wrong and it sits in a drawer. Here's every common size, what each does best, and which suits how you work.
And because we make leather covers, we'll flag which sizes fit our covers and which slip into a pocket.
Notebook Size Chart
Here's the full range in one place, in millimetres and inches, with what each size does best.
| Size | mm | inches | Best for |
|---|---|---|---|
| A7 | 74 × 105 | 2.9 × 4.1 | Quick notes on the go |
| Passport | 90 × 125 | 3.5 × 4.9 | Travel journaling |
| 90 × 140 | 3.5 × 5.5 | EDC lists, jotting | |
| A6 | 105 × 148 | 4.1 × 5.8 | Compact journaling |
| B6 | 125 × 176 | 4.9 × 6.9 | Portable journals, planners |
| Regular TN | 110 × 210 | 4.3 × 8.3 | Traveler's notebooks |
| A5 | 148 × 210 | 5.8 × 8.3 | Daily journaling, bullet journals |
| B5 | 176 × 250 | 6.9 × 9.8 | Study, sketching, projects |
| A4 | 210 × 297 | 8.3 × 11.7 | Desk work, detailed notes |
How Notebook Sizes Work: The A and B Series
Most notebook sizes come from the ISO 216 standard, split into two series. The A-series, A4, A5, A6 and so on, is the one you'll meet most. Its clever feature is the √2 aspect ratio: fold any A-size in half and you get the next size down. An A4 folded in half is exactly two A5 sheets; an A5 folded is two A6. That's why the sizes nest so neatly.
The B-series, B5 and B6, fills the gaps between A-sizes, giving you options that are a little larger than the A-size below them. B5, for instance, sits between A5 and A4 in size — bigger than A5, smaller than A4.
One catch: ISO B5 vs Japanese JIS B5
Here's something most guides miss. Japan uses its own B-series, JIS, and it's slightly larger than the international ISO B-series. ISO B5 is 176 × 250 mm, while JIS B5 is 182 × 257 mm — a touch taller and wider. The same applies to B6. It matters when matching a notebook to a cover: a Japanese-brand B5, Kokuyo, Midori or Hobonichi, won't sit identically to a European-brand ISO B5, Leuchtturm1917 or Rhodia. If you're buying a cover for a specific notebook, check which standard it follows.
The Most Popular Sizes, Explained
A5 148 × 210 mm — the all-rounder
If there's a default notebook size, it's A5. It hits the sweet spot between writing room and portability: big enough for journaling, meeting notes and bullet-journal spreads, small enough to slip into most bags. It's the default for bullet journaling and the safest choice if you're not sure what you want. It's also the size most of our covers are built around.
B5 176 × 250 mm — room to spread out
B5 gives you noticeably more writing space than A5 without the bulk of A4. It's a favourite of students and anyone doing detailed notes, sketches, diagrams or large bullet-journal layouts. Sometimes called the composition size, it's the one to reach for when you want generous spreads but still want to carry it around.
A4 210 × 297 mm — the desk workhorse
A4 is the classic office and study size, matching standard printer paper so handwritten notes and printouts live together neatly. It gives the most room for detailed writing, drawing and presentations, which makes it ideal for big projects and extensive planning. The trade-off is portability — it's the least pocketable size, so it's best as a desk or bag notebook rather than an everyday carry.
A6 105 × 148 mm — pocket-friendly
A6 is built for portability: small enough for a pocket or small bag, yet still roomy enough for quick notes, reminders and compact journaling. It's a great companion for capturing thoughts on the move without carrying anything bulky.
B6 125 × 176 mm — the Goldilocks size
B6 sits just above A6, offering a bit more writing space while staying easy to carry in a bag or large pocket. It's a popular everyday-carry choice for personal journaling, quick lists and planners — big enough to be useful, small enough to stay practical.
Passport 90 × 125 mm — for travellers
Named for matching a real passport's dimensions, this size is made for the road. It's a favourite for travel journals, daily diaries and noting down quotes or sketches, and it tucks easily into a jacket pocket or bag alongside your actual travel documents.
Which Notebook Fits Which Bag or Pocket?
One of the most practical questions — and one we get a lot as a bag and cover maker — is simply: will it fit? Here's a rough guide for a standard 200-page notebook.
| Where | Fits up to |
|---|---|
| Shirt or jacket pocket | A7, Passport, Pocket |
| Back jeans pocket | A7, Passport, Pocket, A6 |
| Small crossbody bag | Up to B6 comfortably, A5 tight |
| Everyday sling or tote | Up to A5 easily, B5 in a tote |
| Daypack or work bag | Up to A4 |
| 13 inch laptop sleeve | A5, B5, A4 |
If a size only fits "tight," it's usually worth dropping to the next size down for comfortable daily carry.
Which Notebook Size Should You Choose?
It comes down to where and how you'll use it:
- Pocket portability: A7, Passport or A6 — small enough to carry anywhere.
- Everyday carry: Pocket, A6 or B6 — the balance of portable and usable.
- Journaling and planning: A5 or B6 — enough room for expressive writing and structured layouts.
- Study or desk work: B5 or A4 — maximum space for detailed notes and projects.
- Not sure? A5 is the safe all-rounder, and the easiest size to find covers and refills for.
Dressing Your Notebook: Leather Covers
Once you've settled on a size, a full-grain leather cover protects the notebook, ages beautifully with use, and lets you refill the same cover for years rather than replacing the whole thing. We build our leather notebook covers around the standard sizes — A5, A6, B6 and A4 — so it's worth landing on your size first, then matching the cover. A quick tip: if your notebook is a Japanese brand, double-check whether it's JIS or ISO sizing before ordering a cover, since the few millimetres can affect the fit.
Frequently Asked Questions
What is the most popular notebook size?
A5, 148 × 210 mm, is the most widely used notebook size, especially for journaling, planning and bullet journals. It balances enough writing room with easy portability, which is why it's the default for most people. B6 and A6 are popular choices for everyday carry.
What is the standard notebook size?
It depends on use. A4, 210 × 297 mm, is the standard for offices and schools because it matches printer paper, while A5 is the standard for personal notebooks and journals. In the US, Letter size, 216 × 279 mm, fills the A4 role.
Is A5 half the size of A4?
Yes. A5 is exactly half the area of A4 — fold an A4 sheet in half along its longer edge and you get an A5 sheet. This halving relationship holds throughout the A-series, so every size folded in half becomes the next size down.
Which is bigger, A5 or B5?
B5, 176 × 250 mm, is larger than A5, 148 × 210 mm. The B-series sizes sit between the A-sizes, so B5 is bigger than A5 but smaller than A4, giving you extra writing space without the full bulk of A4.
What's the difference between ISO B5 and JIS B5?
ISO B5, the international standard, is 176 × 250 mm, while Japanese JIS B5 is slightly larger at 182 × 257 mm. Japanese brands like Kokuyo, Midori and Hobonichi use JIS; European brands like Leuchtturm1917 and Rhodia use ISO. The difference matters when matching a cover to a notebook.
What size is a passport notebook?
A passport notebook is about 90 × 125 mm, roughly the dimensions of an actual passport. It's a popular travel-journal size because it tucks easily into a jacket pocket or bag alongside your real travel documents.
What size notebook is best for bullet journaling?
A5, 148 × 210 mm, is the default for bullet journaling. It gives enough room for monthly calendars, weekly spreads, habit trackers and daily entries while staying portable enough to carry every day. B6 is a good more-compact alternative.
What notebook size fits in a jacket pocket?
Passport, Pocket, A7 and A6 sizes all fit comfortably in a jacket or shirt pocket. B6 may fit a roomier jacket pocket but can be tight. For reliable pocket carry, stick to A6 and smaller.
What's the biggest common notebook size?
Among everyday notebooks, A4, 210 × 297 mm, is the largest in common use — ideal for desk work and detailed projects. Larger sizes like A3 exist but are usually for art and presentations rather than note-taking.
Final Thoughts
There's no single best notebook size — only the right one for how you write and where you carry it. A5 is the safe all-rounder, B5 and A4 give you room to spread out, and A6, Pocket and Passport sizes go everywhere with you. Once you know your size, a full-grain leather cover is what turns a disposable notebook into something you'll keep refilling for years.
Browse our leather notebook covers in A5, A6, B6 and A4 below. Free shipping, with Afterpay, Zippay and Klarna available, and every full-price piece backed by a 365-day warranty.