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By onemall 
Last updated: 2026-10-22.
TL;DR
B5 paper size in Japan is 182 × 257 mm (18.2 × 25.7 cm, 7.17 × 10.12 inches) — that is JIS B5. The international ISO B5 is a different, smaller sheet: 176 × 250 mm (6.93 × 9.84 in). If a notebook, binder or printer setting comes from Japan, “B5” almost always means JIS B5. B4 is 257 × 364 mm, B6 is 128 × 182 mm, and the “semi-B5” (semi B5) Campus school notebook is 179 × 252 mm.
- Is B5 bigger than A5? Yes — JIS B5 has 1.5 times the area of A5.
- B5 vs A4: B5 is smaller, about 75% of an A4 sheet.
- B5 vs US Letter: B5 is narrower and shorter than 8.5 × 11 in.
- JIS B5 vs ISO B5: the Japanese sheet is about 6% larger.
As of October 2026, Japan still uses its own B series. This guide gives every Japanese paper size in mm, cm and inches, explains the JIS vs ISO difference that trips up printers and binder buyers, and lists the notebook sizes and ruling codes you will meet when buying stationery from Japan.
B5 Paper Size in Japan: Why There Are Two B5s
Japan’s paper sizes are set by the industrial standard JIS P 0138, established in 1951 and based on a 1929 national standard for finished paper sizes. It defines two series: an A series identical to the ISO A series, and a JIS B series whose sheets have 1.5 times the area of the A sheet with the same number. JIS B0 is therefore 1.5 m², and the B sizes are not compatible with the international ISO B series.[1][2] ISO B sizes, by contrast, sit at the geometric mean between two A sizes, so ISO B5 is a little smaller than JIS B5.
That is why a “B5 binder” from Japan may not fit “B5” paper printed elsewhere, and why Japanese copiers and print dialogs list both: a common label is B5 (JIS) next to B5 or ISO B5. Web page styling (CSS) recognises the Japanese sizes JIS-B4 and JIS-B5 alongside A3, A4, A5, B4 and B5 for this reason.[1]
B5 Paper Size Chart: JIS B Series in mm, cm and Inches
| Size | mm | cm | inches |
|---|---|---|---|
| JIS B0 | 1030 × 1456 mm | 103 × 145.6 cm | 40.55 × 57.32 in |
| JIS B1 | 728 × 1030 mm | 72.8 × 103 cm | 28.66 × 40.55 in |
| JIS B2 | 515 × 728 mm | 51.5 × 72.8 cm | 20.28 × 28.66 in |
| JIS B3 | 364 × 515 mm | 36.4 × 51.5 cm | 14.33 × 20.28 in |
| JIS B4 | 257 × 364 mm | 25.7 × 36.4 cm | 10.12 × 14.33 in |
| JIS B5 | 182 × 257 mm | 18.2 × 25.7 cm | 7.17 × 10.12 in |
| JIS B6 | 128 × 182 mm | 12.8 × 18.2 cm | 5.04 × 7.17 in |
| JIS B7 | 91 × 128 mm | 9.1 × 12.8 cm | 3.58 × 5.04 in |
| JIS B8 | 64 × 91 mm | 6.4 × 9.1 cm | 2.52 × 3.58 in |
| JIS B9 | 45 × 64 mm | 4.5 × 6.4 cm | 1.77 × 2.52 in |
| JIS B10 | 32 × 45 mm | 3.2 × 4.5 cm | 1.26 × 1.77 in |
Inches are rounded to two decimals from the millimetre values. The JIS B5 paper size in inches is 7.17 × 10.12 in; the B4 paper size (JIS B4) is 10.12 × 14.33 in; B6 size is 5.04 × 7.17 in. Each size is half of the one above it, cut across the long side, so two B5 sheets make one B4 and two B6 sheets make one B5.
ISO B Paper Sizes (International B5, B4, B6)
| Size | mm | cm | inches |
|---|---|---|---|
| ISO B0 | 1000 × 1414 mm | 100 × 141.4 cm | 39.37 × 55.67 in |
| ISO B1 | 707 × 1000 mm | 70.7 × 100 cm | 27.83 × 39.37 in |
| ISO B2 | 500 × 707 mm | 50 × 70.7 cm | 19.69 × 27.83 in |
| ISO B3 | 353 × 500 mm | 35.3 × 50 cm | 13.90 × 19.69 in |
| ISO B4 | 250 × 353 mm | 25 × 35.3 cm | 9.84 × 13.90 in |
| ISO B5 | 176 × 250 mm | 17.6 × 25 cm | 6.93 × 9.84 in |
| ISO B6 | 125 × 176 mm | 12.5 × 17.6 cm | 4.92 × 6.93 in |
| ISO B7 | 88 × 125 mm | 8.8 × 12.5 cm | 3.46 × 4.92 in |
| ISO B8 | 62 × 88 mm | 6.2 × 8.8 cm | 2.44 × 3.46 in |
| ISO B9 | 44 × 62 mm | 4.4 × 6.2 cm | 1.73 × 2.44 in |
| ISO B10 | 31 × 44 mm | 3.1 × 4.4 cm | 1.22 × 1.73 in |
Europe, China and most printers outside Japan use these. If you search “B5 size in cm” you will see both 17.6 × 25 cm (ISO) and 18.2 × 25.7 cm (JIS); both are correct for their own standard. When a listing on a Japanese site gives no standard, assume JIS.
A Series and US Sizes for Comparison (A4, A5, Letter, Legal)
| Size | mm | cm | inches |
|---|---|---|---|
| A0 | 841 × 1189 mm | 84.1 × 118.9 cm | 33.11 × 46.81 in |
| A1 | 594 × 841 mm | 59.4 × 84.1 cm | 23.39 × 33.11 in |
| A2 | 420 × 594 mm | 42 × 59.4 cm | 16.54 × 23.39 in |
| A3 | 297 × 420 mm | 29.7 × 42 cm | 11.69 × 16.54 in |
| A4 | 210 × 297 mm | 21 × 29.7 cm | 8.27 × 11.69 in |
| A5 | 148 × 210 mm | 14.8 × 21 cm | 5.83 × 8.27 in |
| A6 | 105 × 148 mm | 10.5 × 14.8 cm | 4.13 × 5.83 in |
| A7 | 74 × 105 mm | 7.4 × 10.5 cm | 2.91 × 4.13 in |
| US Letter | 216 × 279 mm | 21.6 × 27.9 cm | 8.50 × 11.00 in |
| US Legal | 216 × 356 mm | 21.6 × 35.6 cm | 8.50 × 14.00 in |
| Tabloid / Ledger | 279 × 432 mm | 27.9 × 43.2 cm | 11.00 × 17.00 in |
The A series is the same in Japan and internationally (US Letter, Legal and Tabloid are shown for reference), so an A4 or A5 notebook from Japan matches A4/A5 paper and covers anywhere outside North America.
B5 vs A4, A5 and Letter: Which Is Bigger?
| Comparison | Dimensions | JIS B size vs the other sheet |
|---|---|---|
| B5 vs A4 | 182 × 257 mm vs 210 × 297 mm | 75% of the area — smaller |
| B5 vs A5 | 182 × 257 mm vs 148 × 210 mm | 150% of the area — larger |
| B5 vs US Letter | 182 × 257 mm vs 215.9 × 279.4 mm | 78% of the area — smaller |
| B4 vs A4 | 257 × 364 mm vs 210 × 297 mm | 150% of the area — larger |
| B4 vs A3 | 257 × 364 mm vs 297 × 420 mm | 75% of the area — smaller |
| B6 vs A5 | 128 × 182 mm vs 148 × 210 mm | 75% of the area — smaller |
| B6 vs A6 | 128 × 182 mm vs 105 × 148 mm | 150% of the area — larger |
| JIS B5 vs ISO B5 | 182 × 257 mm vs 176 × 250 mm | 106% of the area — larger |
Common questions, answered from the table:
- Is B5 bigger than A4? No. B5 is smaller than A4, about three quarters of the area.
- A5 or B5 — which is bigger? B5. It sits between A5 and A4, which is why many students prefer it: more room than A5, lighter than A4.
- Is B5 half of A4? No — A5 is half of A4. B5 is half of B4.
- B4 size vs A4: B4 is larger than A4 but smaller than A3.
- B6 vs A5: B6 is smaller than A5; it is a common Japanese planner and pocket-notebook size.
- B5 compared to letter size: about 1.33 in narrower and 0.88 in shorter, so a B5 notebook fits in a letter-size bag or binder sleeve with room to spare, but a letter sheet will not fit inside a B5 binder.
Semi-B5, AB and Other Japanese Notebook and Book Sizes
| Name | Size | Typical use |
|---|---|---|
| Semi-B5 (セミB5) | 179 × 252 mm | Kokuyo Campus and other Japanese school notebooks; slightly smaller than JIS B5 |
| AB (AB判) | 210 × 257 mm | Width of A4, height of JIS B5; magazines and some workbooks |
| Bunko (文庫判) | A6, 105 × 148 mm | Paperback novels |
| Shinsho / B40 (新書判) | about 103 × 182 mm | Non-fiction paperbacks; the B40 cut is JIS B1 divided into 4 × 10 |
| Shiroku-ban (四六判) | about 127 × 188 mm | Hardcover and literary books |
| Kiku-ban (菊判) | about 152 × 218 mm | Academic and art books |
The everyday Japanese school notebook is semi-B5: a Kokuyo Campus semi-B5 notebook (model ノ-5AN, A-ruled 7 mm, 30 lines) is listed at 252 × 179 mm, the size of Japan’s standard school notebook.[3] Kokuyo launched the Campus line for students nationwide in 1975.[4] Semi-B5 notebooks fit JIS B5 covers and B5 binder pockets. The AB, shiroku and kiku book sizes are trade conventions rather than exact standards, so measure the listing photo if a cover or case must fit; the Japanese book sizes above are typical values.[2]
Measurement quick reference: the B5 measurement is 182 × 257 mm (the actual, real size of the trimmed sheet), the B4 measurement 257 × 364 mm and the B6 measurement 128 × 182 mm. Measurements for A5 versus B5: 148 × 210 mm against 182 × 257 mm, so B5 is the bigger one. A “large B5” in a listing usually means a B5 notebook or binder, not a different paper standard; the cover is a few millimetres larger than the paper inside. DIN A5 and ISO B5 follow the German DIN 476 system that became ISO 216.[1]
B5, B4 and B6: Ratio, Diagonal, Points, Pixels and Landscape
| Size | Aspect ratio | Diagonal | Points (1/72 in) | Pixels at 300 dpi | Landscape (horizontal) |
|---|---|---|---|---|---|
| JIS B4 | 1 : 1.416 | 445.6 mm (17.54 in) | 729 × 1032 pt | 3035 × 4299 px | 364 × 257 mm |
| JIS B5 | 1 : 1.412 | 314.9 mm (12.40 in) | 516 × 729 pt | 2150 × 3035 px | 257 × 182 mm |
| JIS B6 | 1 : 1.422 | 222.5 mm (8.76 in) | 363 × 516 pt | 1512 × 2150 px | 182 × 128 mm |
Every A and B sheet keeps roughly the same 1 : 1.414 (√2) ratio — the “silver ratio” — which is why a B4 page reduces to B5 or enlarges to A3 on a copier without cropping. Points are what InDesign and PDF tools use; the pixel size at a given resolution is what image editors need, and pixels at 300 dpi are the usual print-quality target, and at 96 dpi a JIS B5 page is about 688 × 971 px. If a printer asks for a B5 size with bleed, add 3 mm on each side: 188 × 263 mm. B4 measured in feet is about 0.84 × 1.19 ft.
What Is B5 Paper Used For? (And B4 and B6)
- B5: school notebooks, loose-leaf filler paper, workbooks, a flyer, leaflet or brochure, a restaurant menu and magazines; manga fan comics (doujinshi) are commonly printed at B5, and Deleter sells its A4 manuscript paper with a 182 × 257 mm B5 frame “for B5 / doujinshi”.[7]
- B4: a copy of two B5 pages side by side, a leaflet or menu, glossy or matte posters, test sheets, display files and the manga manuscript paper used by professionals and for magazine submissions — Deleter labels its B4 sheets “pro / submission”, and IC’s B4 manuscript paper is 257 × 364 mm with a 220 × 310 mm finished-page frame.[7][8] Manga paper weight such as 110 kg or 135 kg is the weight of 1,000 sheets of the 788 × 1,091 mm shiroku base sheet, so 135 kg Kent paper is thicker than 110 kg — the B4 paper type to choose if you ink with a dip pen.[8]
- B6: planners, pocket notebooks, a small flyer, and books; B6 size versus A5 is about 75% of the area. A passport (125 × 88 mm closed) is smaller than B6.
Other Japanese paper sizes people ask about: standard origami paper is a 15 × 15 cm square (Toyo’s everyday origami packs, for example, are 15 cm). For manga paper, see B4 above.
A5 vs B5: Which Is Better for Note Taking and School?
For note taking, B5 gives about 50% more writing area than A5 while staying smaller than A4 and US letter (8.5 x 11). That is why B5 is the normal notebook size in Japanese schools. A5 is easier to carry and better for a planner or journal. B5 vs A4 for note taking: A4 suits printed handouts you want to keep flat; B5 suits lecture notes. Compared with a standard US composition notebook (about 7.5 × 9.75 in), a B5 notebook is slightly smaller in width and a little taller. There is no exact US equivalent of B5.
B5 Notebook Types: Lined, Unruled, Spiral and Binder
Japanese B5 and semi-B5 notebooks come lined (ruled, with or without a margin), unlined / unruled / plain / blank, grid and dotted. Bindings include stapled or glued (wireless) notebooks that lay flat, spiral and ring notebooks, and refillable ring binder notebooks with filler paper, dividers and tabs. “Thick” notebooks list sheet counts (枚) such as 30, 60 or 80. Thin Japanese papers such as Tomoe River are popular with fountain pen users who want a fountain-pen-friendly notebook. “Slim” versions (B5 slim, B6 slim) keep the height and narrow the width — check the listed millimetres. B4 and B6 spiral notebooks also exist for sketching and pocket use.
Japanese Notebook Ruling: A罫, B罫 and Dot Ruled
| Japanese | Meaning | Line width | Notes |
|---|---|---|---|
| A罫 | A-ruled | 7 mm | The everyday ruled line in Japan; close to US college rule (9/32 in, about 7.1 mm) |
| B罫 | B-ruled | 6 mm | Close to US narrow rule (1/4 in, about 6.35 mm) |
| C罫 | C-ruled | 5 mm | Narrow rule for small handwriting |
| U罫 | U-ruled | 8 mm | Wide; US wide rule is 11/32 in, about 8.7 mm |
| UL罫 | UL-ruled | 10 mm | Extra-wide, for young children |
| 方眼罫 | Graph / grid | usually 5 mm | Square grid |
| ドット入り罫 | Dot-ruled | per line width | Ruled lines with dots that line up as a grid |
Kokuyo’s own product filters list A-ruled at 7 mm, B-ruled at 6 mm, C-ruled at 5 mm, U-ruled at 8 mm and UL-ruled at 10 mm, plus dotted versions of each.[5] If you are buying a B5 notebook for small, neat handwriting, look for B罫; for diagrams, 方眼 (grid).
B5 Binders, Loose-Leaf and Covers
A B5 binder from Japan takes 26-hole loose-leaf (ルーズリーフ) in JIS B5 (182 × 257 mm), while A4 loose-leaf uses 30 holes and A5 uses 20 holes — Maruman, for example, sells each refill in exactly those three hole counts.[6] Check the hole count in the listing (26穴 / 30穴 / 20穴) before you buy refill paper: the holes, not just the sheet size, must match. Clear-pocket files (クリアファイル) and document cases are sold in B5, A4 and B4 widths, so if you print on US Letter at home, an A4 file is the closest Japanese size that will hold it.
The same sizes run through filing — search “B5 file folder”, “B4 document folder”, “B5 zip folder”, “B6 folder” or “B4 box” — with B5 and B4 file folders, document folders, display folders and display books (clear books), zip folders, expanding / accordion folders, sheet protectors, transparent binders and ring file folders. A B5 binder mechanism is sold by ring count (26 binder rings for B5; 2-ring and 6-ring styles exist too), alongside a matching hole punch, separator sheets and binder clip; B5 binders with a zipper or a wide spine are available for thick notes.
Notebook covers sold for “B5” usually fit both semi-B5 and JIS B5 notebooks. Planner covers for B6 fit B6 notebooks; Hobonichi and many Japanese diaries also come in A5 and A6, so read the size code in the product name.
Printing on B5: Word, Canva and Home Printers
For copies and scanning, check whether your copier or scanner can detect JIS B5 and B4; if it cannot, set a custom size. In your printer driver (Brother, Epson, Canon, HP and others), look for “JIS B5” or “B5 (JIS)” before falling back to a custom size.
To print a B5 page in Microsoft Word, Google Docs or Canva, choose a custom size of 182 × 257 mm (7.17 × 10.12 in) if “B5 (JIS)” is not in the list; choose 176 × 250 mm only if your target is ISO B5. Many home printers accept B5 through the manual or rear feed with the paper guides moved in. For JIS B4 (257 × 364 mm) you need a printer with a legal-length or larger tray. In pixels at 300 dpi, JIS B5 is about 2150 × 3035 px and JIS B4 about 3035 × 4299 px.
How to Buy B5 Notebooks and Japanese Stationery From Japan
- Search in Japanese with the size: キャンパスノート セミB5, B5 ルーズリーフ 26穴, B6 手帳, B4 画用紙.
- Read the size line: listings write セミB5 (semi-B5), B5 (JIS), A5 or B6 and the hole count for loose-leaf.
- Bundle light items: paper is heavy for its size, so combining notebooks with other purchases into one parcel usually lowers shipping per item.
- See it before it ships: wrong/missing-item checks (¥200) and unboxing photos (¥500 / ¥700) let you confirm the exact size and ruling at the Tokyo warehouse.
OneMall buys from Japanese marketplaces such as Mercari, Yahoo Auctions, Rakuten and Amazon Japan, and from other Japanese online stores through LinkBuy. Items that need a lottery entry, purchase limit, Japanese identity verification or a merchant account cannot be purchased.
Service fees are ¥300 per item on most marketplaces; from ¥200 per item on Yahoo Auctions and LinkBuy. The first six orders consolidate free; each additional order costs ¥100. Storage is free for 90 days after arrival (30 days after consolidation). Payment is by Visa, Mastercard or PayPal, settled in USD.
US buyers: since August 29, 2025, US-bound parcels of any value go through customs and pay applicable duties, taxes and fees — the $800 de minimis exemption no longer applies. OneMall currently ships to the United States by ECMS and DHL; the live quote at checkout shows which lines accept your parcel.
Browse semi-B5 notebook listings or B5 loose-leaf listings, read our Japanese stationery brands guide for Kokuyo, Midori, Maruman and more, and compare the best Japan proxy services and the cheapest Japan proxy options by total landed cost. Converting clothes instead of paper? See the Japanese clothing size conversion chart; for ita bags sized A4 or A3, the ita bag size guide.
Frequently Asked Questions
What size is B5 paper in inches?
JIS B5, the Japanese size, is 7.17 × 10.12 inches (182 × 257 mm). ISO B5 is 6.93 × 9.84 inches (176 × 250 mm).
What is B5 size in cm?
18.2 × 25.7 cm for JIS B5; 17.6 × 25 cm for ISO B5.
What does JIS B5 mean?
The B5 sheet defined by Japanese Industrial Standard P 0138. JIS B sheets have 1.5 times the area of the matching A sheet, so they are slightly larger than ISO B sheets.
What size is B4 paper?
JIS B4 is 257 × 364 mm (10.12 × 14.33 in). ISO B4 is 250 × 353 mm.
What size is B6?
JIS B6 is 128 × 182 mm (5.04 × 7.17 in); ISO B6 is 125 × 176 mm.
What is semi-B5?
The Japanese school-notebook size, 179 × 252 mm (7.05 × 9.92 in) on Kokuyo Campus notebooks — a little smaller than a JIS B5 sheet.
What is B5 format used for?
In Japan: school notebooks, loose-leaf, workbooks, flyers, magazines and doujinshi. B4 is used for copies and manga manuscript paper; B6 for planners and books.
Is B5 size greater than A4?
No. A4 (210 × 297 mm) is larger; B5 is about 75% of it. B4 is the B size greater than A4.
What is the B5 aspect ratio?
About 1 : 1.41 (257 ÷ 182), the same √2 ratio as A sizes.
Is B5 the same as letter size?
No. Letter is 8.5 × 11 in (216 × 279 mm); B5 is smaller on both sides.
Why do Japanese notebooks use B5 instead of A4?
B5 has been the standard school and office notebook size in Japan for decades, and the JIS B series fills the gap between A sizes. It is big enough for notes and light enough to carry.
References
- Paper size — Japanese variation (Wikipedia). https://en.wikipedia.org/wiki/Paper_size
- 紙の寸法 — JIS P 0138 (Wikipedia, Japanese). https://ja.wikipedia.org/wiki/%E7%B4%99%E3%81%AE%E5%AF%B8%E6%B3%95
- Tanomail, Kokuyo Campus notebook semi-B5 ノ-5AN specification (252 × 179 mm). https://www.tanomail.com/product/0163620/
- Kokuyo, History of Campus Notebooks. https://www.kokuyo.com/stationery/lp/campus-notebook/history
- Kokuyo stationery search filters (ruling widths). https://www.kokuyo.com/stationery/search/
- Maruman loose-leaf product list (A4 30 holes / B5 26 holes / A5 20 holes). https://www.e-maruman.co.jp/lp/maruman-loose-leaf/products.html
- Deleter manga manuscript paper (A4 for B5/doujinshi, B4 pro/submission). http://www.deleter.jp/deleter_genkou.htm
- IC manga manuscript paper B4 (257 × 364 mm). https://www.icscr.jp/products/genko_135-b4/