---
title: 'B4 paper size: ISO 250 × 353 mm or JIS 257 × 364 mm?'
url: https://joelin.cc/en/p/9613
source: https://joelin.cc/en/p/9613
lang: en
pubDate: '2026-10-30'
date_modified: '2026-10-30'
description: Compare ISO and JIS B4 dimensions, B5 folding, A4/A3 sizes and print pixels. Check the standard before choosing paper or scaling a document.
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: What are the B4 dimensions in centimetres?
    a: JIS B4 is 25.7 × 36.4 cm (257 × 364 mm); ISO B4 is 25 × 35.3 cm (250 × 353 mm). Taiwan generally uses JIS for copiers and examination papers.
  - q: How much bigger is B4 than A4?
    a: JIS B4 is about 4.7 cm wider and 6.7 cm longer than A4 (21 × 29.7 cm), with approximately 1.5 times its area. It is smaller than A3 (29.7 × 42 cm).
  - q: How many B5 sheets make B4?
    a: 'Two within the same standard. Two JIS B5 sheets of 18.2 × 25.7 cm make 36.4 × 25.7 cm: B4 turned sideways. Folding reverses this relationship; nominal rounded sizes are not a precision cutting specification.'
  - q: How many pixels does B4 need?
    a: 'At 300 DPI: JIS 3035 × 4299 px; ISO 2953 × 4169 px. JIS at 150 DPI is 1518 × 2150 px. Use 300 DPI for close reading and generally 150 DPI for internal reports.'
  - q: Can convenience stores print B4?
    a: In Taiwan, the ibon, FamiPort and Hi-Life cloud-printing lists checked on 2026-10-19 did not offer B4. Use a copy shop or scale the document to A4 or A3. This is not a claim about stores worldwide.
  - q: Where can I print B4?
    a: Try a copy shop, print centre or a school/office copier that supports the required B4 standard. Specify the dimensions; Taiwan’s cited convenience-store cloud services do not provide B4.
translation_of: /p/9613
---

# B4 paper size: ISO 250 × 353 mm or JIS 257 × 364 mm?

B4 measures 25 × 35.3 cm under ISO, or 25.7 × 36.4 cm under JIS. A sheet larger than A4 but smaller than A3 may be B4, but its name alone does not identify the dimensions.

## Two B4 standards

| Standard | cm | mm |
| --- | --- | --- |
| ISO B4 | 25 × 35.3 | 250 × 353 |
| JIS B4 | 25.7 × 36.4 | 257 × 364 |

In Taiwan, copier settings, school examination papers and sheet music labelled B4 generally use JIS. ISO B4 appears in international specifications and some European equipment. The short edges differ by 0.7 cm and the long edges by 1.1 cm; choosing the wrong page size can cause white margins or cropped edges.

## Why ISO and JIS differ

The A series has one international size system, while ISO and JIS define the B series from different starting points. Japanese B sizes are slightly larger. Taiwan’s printing and office equipment have long been influenced by Japanese systems; this does not establish the convention in every other country. For example, JIS B5 is 18.2 × 25.7 cm, while ISO B5 is 17.6 × 25 cm.

## B4 folds to B5

| Size | cm |
| --- | --- |
| JIS B3 | 36.4 × 51.5 |
| JIS B4 | 25.7 × 36.4 |
| JIS B5 | 18.2 × 25.7 |
| JIS B6 | 12.8 × 18.2 |

Each step in the B series halves the area; the design preserves a 1:√2 aspect ratio. Two JIS B5 sheets placed side by side make a JIS B4 footprint. Fold B4 once for B5, then again for B6. In Taiwan, folding examination papers this way makes them easier to file.

```mermaid
flowchart TB
  A["JIS B4<br/>257 × 364 mm"] -->|Half-fold| B["JIS B5<br/>182 × 257 mm"]
  B -->|Half-fold| C["JIS B6<br/>128 × 182 mm"]
```

Schematic only; nominal whole-millimetre sizes can include rounding differences. This is not a precision cutting plan.

## Between A4 and A3

| Size | cm |
| --- | --- |
| A3 | 29.7 × 42 |
| JIS B4 | 25.7 × 36.4 |
| A4 | 21 × 29.7 |

JIS B4 is about 4.7 cm wider and 6.7 cm longer than A4, with roughly 1.5 times its area. It is about 4 cm narrower and 5.6 cm shorter than A3. It gives more layout space without taking up as much desk space as A3.

## What B4 is used for

- Examination papers: in Taiwan, B4 provides about half as much space again as A4 and folds to B5.
- Sheet music: more staff lines fit without squeezing the spacing, reducing page turns.
- Reports and forms: a compromise when A4 cannot accommodate all the columns.
- Notices and programmes: useful for a newspaper-like layout.

## Pixels for printing

| Standard | px |
| --- | --- |
| JIS · 300 DPI | 3035 × 4299 |
| JIS · 150 DPI | 1518 × 2150 |
| ISO · 300 DPI | 2953 × 4169 |

Calculate pixels as millimetres ÷ 25.4 × DPI. Use 300 DPI for close reading such as examinations and music; 150 DPI is usually sufficient for internal reports and draft prints. Ask the printer whether its B4 is ISO or JIS before preparing the file.

## Printing and scaling

In Taiwan, the official cloud-printing paper lists for 7-Eleven ibon, FamilyMart FamiPort and Hi-Life did not include B4 when checked on 2026-10-19. They list A4, A3 and 4×6 options (with special paper options at Hi-Life). For B4, ask a copy shop, print centre or a school/office with a suitable copier; confirm availability locally. Otherwise reduce to A4, making text smaller, or enlarge to A3 and trim.

The theoretical scale is about 81.6% from JIS B4 to A4 and 122.4% from A4 to JIS B4. Integer settings of 81% and 122% respectively help keep the page within the paper; the machine’s actual printable area still applies.

[ibon](https://print.ibon.com.tw/spec) · [FamiPort](https://print.famiport.com.tw/q-and-a) · [Hi-Life](https://hilife.creatify.tw/)

[Related: B6 sizes](/en/p/9475)

## Frequently asked questions

### What are the B4 dimensions in centimetres?

JIS B4 is 25.7 × 36.4 cm (257 × 364 mm); ISO B4 is 25 × 35.3 cm (250 × 353 mm). Taiwan generally uses JIS for copiers and examination papers.

### How much bigger is B4 than A4?

JIS B4 is about 4.7 cm wider and 6.7 cm longer than A4 (21 × 29.7 cm), with approximately 1.5 times its area. It is smaller than A3 (29.7 × 42 cm).

### How many B5 sheets make B4?

Two within the same standard. Two JIS B5 sheets of 18.2 × 25.7 cm make 36.4 × 25.7 cm: B4 turned sideways. Folding reverses this relationship; nominal rounded sizes are not a precision cutting specification.

### How many pixels does B4 need?

At 300 DPI: JIS 3035 × 4299 px; ISO 2953 × 4169 px. JIS at 150 DPI is 1518 × 2150 px. Use 300 DPI for close reading and generally 150 DPI for internal reports.

### Can convenience stores print B4?

In Taiwan, the ibon, FamiPort and Hi-Life cloud-printing lists checked on 2026-10-19 did not offer B4. Use a copy shop or scale the document to A4 or A3. This is not a claim about stores worldwide.

### Where can I print B4?

Try a copy shop, print centre or a school/office copier that supports the required B4 standard. Specify the dimensions; Taiwan’s cited convenience-store cloud services do not provide B4.

Sources: Chinese source first published 2026-08-18; revised 2026-10-30. Taiwan printing examples and cloud-printing check dated 2026-10-19; ISO and JIS must be distinguished.

AI-assisted translation and editing: Asaki (AI)

[Original article](/p/9613)