--- title: 'B5 paper size: ISO 176 × 250 mm and JIS 182 × 257 mm' url: https://joelin.cc/en/p/9608 source: https://joelin.cc/en/p/9608 lang: en pubDate: '2026-10-30' date_modified: '2026-10-30' description: 'B5 comes in two standards: ISO 17.6 × 25 cm and JIS 18.2 × 25.7 cm. Compare A4 and A5, notebook sizes, folding relationships and print pixels.' schema_type: BlogPosting author: joe entity_ids: author: https://me.joelin.cc/#joe ai_role: ai_only translation_assistant: asaki ai_credit: 'AI-assisted translation and editing: Asaki (AI)' faq: - q: How big is B5 in centimetres? a: ISO B5 is 17.6 × 25 cm; JIS B5 is 18.2 × 25.7 cm. Notebooks and school handouts in Taiwan generally use JIS. - q: Which B5 size do notebooks use? a: In the Taiwanese notebook market described here, JIS B5 (182 × 257 mm) is prevalent because of Japanese stationery and publishing supply chains. Check the measurements when buying elsewhere. - q: Is B5 bigger than A4? a: No. A4 is 21 × 29.7 cm and has about 33% more area than JIS B5. Conversely, JIS B5 has about 25% less area than A4. - q: Is B5 bigger than A5? a: Yes. JIS B5 has about 50% more area than A5 (14.8 × 21 cm). A5 or B6 is more suitable when you want a smaller format. - q: How many pixels does B5 need at 300 DPI? a: ISO B5 needs 2079 × 2953 px; JIS B5 needs 2150 × 3035 px. Confirm the exact millimetre dimensions with the printer. - q: What is the relationship between B5 and B6? a: Folding B5 in half gives the nominal B6 format in the same standard. JIS B6 is 128 × 182 mm; two JIS B5 sheets correspond to JIS B4. Whole-millimetre rounding can cause small differences. translation_of: /p/9608 --- # B5 paper size: ISO 176 × 250 mm and JIS 182 × 257 mm B5 has two official sizes: ISO B5 is 17.6 × 25 cm; JIS B5 is 18.2 × 25.7 cm. In Taiwan, notebooks and school handouts labelled B5 generally use the Japanese JIS size. You may be checking how a notebook compares with A4 and A5, or preparing a booklet and wondering why two different B5 measurements appear. Both measurements are valid: the name alone does not identify the standard. ## B5 dimensions: ISO and JIS | Standard | cm | mm | | --- | --- | --- | | ISO | 17.6 × 25 | 176 × 250 | | JIS | 18.2 × 25.7 | 182 × 257 | ISO B5 is used in international printing and some European stationery; JIS B5 is used in Japanese publishing and stationery and is prevalent in Taiwan's notebook market. These market examples do not mean every notebook sold elsewhere follows JIS. ![B5 dimensions in millimetres: ISO 176 × 250 and JIS 182 × 257.](https://image.joelin.cc/cdn-cgi/imagedelivery/0xu8EsaSar9n3zUKY5d7xw/joelin/2026-10/foreign-paper-b5-20261026-body/hero) Image source: joelin.cc, original geometric comparison. All dimensions are in mm; JIS B5 is slightly larger than ISO B5. The difference starts at B0: JIS B0 has a theoretical area of 1.5 m², while ISO B0 has an area of √2 m². The Japanese B series is therefore slightly larger. A Taiwanese notebook measuring 182 × 257 mm has not been measured incorrectly: it is the JIS version. ## Between A4 and A5 | Size | cm | Area vs JIS B5 | | --- | --- | --- | | A4 | 21 × 29.7 | About 33% larger | | JIS B5 | 18.2 × 25.7 | Reference | | ISO B5 | 17.6 × 25 | About 6% smaller | | A5 | 14.8 × 21 | About 33% smaller | The order is A5 < ISO B5 < JIS B5 < A4. JIS B5 is about 25% smaller than A4 when A4 is the denominator; reversing the comparison makes A4 about 33% larger than JIS B5. JIS B5 is also about 50% larger than A5. These percentages compare area, not edge length. B5 offers more writing space than A5 while taking up less room in a bag than A4. This explains its role as a notebook format in the Taiwanese context of the original article. The B series fills intermediate sizes between neighbouring A formats, as B6 does between A6 and A5. ## Fold to B6; combine to B4 - Folding JIS B5 in half gives the nominal JIS B6 format, 12.8 × 18.2 cm, used for planners. - Two JIS B5 sheets side by side correspond to JIS B4, 25.7 × 36.4 cm, used for larger exam sheets and reports in Taiwan. - The B series, like the A series, uses the theoretical 1:√2 aspect ratio. ISO and JIS dimensions must remain within their own series. Standard dimensions are rounded to whole millimetres, so folding is a way to understand the format family, not a precision cutting specification. ## How many pixels for a B5 print? Use: millimetres ÷ 25.4 × DPI. The following values are rounded to whole pixels. | DPI | ISO B5, px | JIS B5, px | | --- | --- | --- | | 300 | 2079 × 2953 | 2150 × 3035 | | 150 | 1039 × 1476 | 1075 × 1518 | At 300 DPI, ISO B5 needs 2079 × 2953 pixels and JIS B5 needs 2150 × 3035. Confirm the standard before preparing artwork. For printing or custom stationery, state 176 × 250 mm or 182 × 257 mm explicitly rather than ordering only “B5”. Further reading: [A4](/en/p/9607), [A5](/en/p/9447), [B6](/en/p/9475), [B4](/en/p/9613) and [pixels and DPI (Chinese)](/p/9086). ## Frequently asked questions ### How big is B5 in centimetres? ISO B5 is 17.6 × 25 cm; JIS B5 is 18.2 × 25.7 cm. Notebooks and school handouts in Taiwan generally use JIS. ### Which B5 size do notebooks use? In the Taiwanese notebook market described here, JIS B5 (182 × 257 mm) is prevalent because of Japanese stationery and publishing supply chains. Check the measurements when buying elsewhere. ### Is B5 bigger than A4? No. A4 is 21 × 29.7 cm and has about 33% more area than JIS B5. Conversely, JIS B5 has about 25% less area than A4. ### Is B5 bigger than A5? Yes. JIS B5 has about 50% more area than A5 (14.8 × 21 cm). A5 or B6 is more suitable when you want a smaller format. ### How many pixels does B5 need at 300 DPI? ISO B5 needs 2079 × 2953 px; JIS B5 needs 2150 × 3035 px. Confirm the exact millimetre dimensions with the printer. ### What is the relationship between B5 and B6? Folding B5 in half gives the nominal B6 format in the same standard. JIS B6 is 128 × 182 mm; two JIS B5 sheets correspond to JIS B4. Whole-millimetre rounding can cause small differences. Sources: First published in Chinese on 17 August 2026; revised on 30 October 2026. Notebook and school-handout examples refer to Taiwan. AI-assisted translation and editing: Asaki (AI) [Original article](/p/9608)