How do you compare different paper sizes? Aside from the standard A4 and B5, what are the C series, Kikuban, and Shirokuban? If you find yourself puzzled by the various paper sizes when you want to print documents, produce products, or customize books, don’t worry. This article will explain the sizes of different paper standards and provide a comparison table for easy reference, helping you understand at a glance!

 

Introduction to Paper Size Specifications

To understand paper sizes, you first need to know what standards exist. Generally, paper specifications can be divided into two main categories:

• ISO International Standards
  

The International Organization for Standardization defines it as including A series (A0, A1, A2, A3, etc.), B series (B0, B1, B2, B3, etc.), and C series (C0, C1, C2, C3, etc.). The sizing method is easy to remember: each size is half the size of the previous one. For example, A1 is half the size of A0, A2 is half of A1, and so on.

• Common Specifications in Taiwan

In Taiwan, when you buy paper at a store, you often see sizes marked as “1K,” “2K,” etc. These specifications apply to Kikuban (GK) and Shirokuban formats, both of which have been used since the Japanese colonial period. The Kikuban size is closer to the ISO A series, while the Shirokuban size aligns more closely with the ISO B series.

💡 Reminder: Manufacturers may slightly adjust the sizes of Kikuban (GK) and Shirokuban formats to align with ISO international standards or printed product dimensions. Therefore, the dimensions from different manufacturers might vary slightly, so it’s essential to pay extra attention when comparing sizes.

Paper Size Comparison Chart: Understanding A, B, C Series, Kikuban, and Shirokuban at a Glance!

After understanding the classification of paper sizes, let’s examine the detailed size comparison chart.

Here’s a quick overview of ISO standard sizes. You can quickly master the dimensions of A0, A1, A3, A4, and A5 paper sizes.

Spec	A Series（mm）	B Series（mm）	C Series（mm）
Size Illustration Diagram
0	841 x 1189	1000 x 1414	917 x 1297
1	594 x 841	707 x 1000	648 x 917
2	420 x 594	500 x 707	458 x 648
3	297 x 420	353 x 500	324 x 458
4	210 x 297	250 x 353	229 x 324
5	148 x 210	176 x 250	162 x 229
6	105 x 148	125 x 176	114 x 162
7	74 x 105	88 x 125	81 x 114
8	52 x 74	62 x 88	57 x 81
9	37 x 52	44 x 62	40 x 57
10	26 x 37	31 x 44	28 x 40

Common Paper Sizes Chart in Taiwan: Understanding 4K, 8K, 16K

Kikuban size	centimeters	Shirokuban size	centimeters
G1K	63.5 x 88.9	1K	78.7 x 109.2
G2K	44.45 x 63.5	2K	54.6 x 78.7
G4K	31.75 x 44.45	4K	39.4 x 54.6
G8K	22.23 x 31.75	8K	27.3 x 39.4
G16K	15.88 x 22.23	16K	19.69 x 27.3
G32K	11.18 x 15.88	32K	13.67 x 19.69
G64K	7.95 x 11.18	64K	9.86 x 13.67
G128K	5.59 x 7.95	128K	6.83 x 9.98

 

How do you convert A4, B5, 8K, and 16K? Comprehensive Paper Size Conversion Table

With so many paper-size specifications, can they be converted? As mentioned, Kikuban is closer to the ISO A series, while Shirokuban aligns more with the ISO B series. Thus, if you want to compare standard sizes, the table below may help:

Standard Sizes	Corresponds to Kikuban	Corresponds to Shirokuban
A4	G8K	10K
A5	G16K	25K
A6	G36K	49K
B4	G4K	8K
B5	G8K	16K
B6	G25K	36K

A4 Size, B5 Size, A5 Size: The Three Most Confusing Paper Sizes

• A4 Size:

  21 cm x 29.7 cm, the most commonly used paper size internationally.

• B5 Size:

  17.6 cm x 25.0 cm, commonly called 16K size in Taiwan for custom notebooks.

• A5 Size:

  14.8 cm x 21.0 cm, commonly referred to as 25K size in Taiwan for custom notebooks.

Common Paper Size Applications: Must-Read for Printing and Design Professionals

Where are the different sizes of paper commonly used? What size books do we usually read? Let’s explore the typical applications of various paper sizes:

• A series, Kikuban ➜ Documents, books, and magazines.

Generally, the A series sizes, such as A4 and A5, are most commonly used for printing documents. These dimensions are also frequently used for producing books, manuals, and magazines.

A4 is one of daily life’s most standard paper sizes, measuring approximately 21 x 29.7 centimeters. This paper is widely used for printing, copying, and document filing. Its moderate size makes it easy to carry while accommodating enough content, making it suitable for various office and academic purposes. Whether writing reports, designing presentations, or creating posters, A4-sized paper is an ideal choice.

• B series, Shirokuban ➜ Posters, art papers, or commercial advertisements.

The B series is commonly used for posters, art papers, or commercial advertisements. Additionally, B5 is also a popular size for printing purposes.

• C Series ➜ Envelope

The C series is mainly used for making envelopes and can correspond to the A series paper sizes. For example, if the letter paper is A4 size, a C4-size envelope can be chosen; if the letter paper is folded in half to A5 size, a C5-size envelope would be suitable.

Extended Content for Leatai Paper Size Guide

📘 A5 vs B5 Paper Size – Which One Should You Choose?

While A4 is widely known, many notebook lovers prefer A5 or B5 for personal use. Here’s a closer comparison:

A5 is ideal for minimalist planners and travel notebooks, while B5 offers a balance of space and manageability—great for school or work.

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📘 A4 vs Letter Size – What’s the Difference?

Though they appear similar, A4 and US Letter are different in dimensions:

If your target market includes North America, consider offering both sizes in your product catalog to avoid compatibility issues.

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📘 8K vs 16K Paper Size – Detailed Comparison

These traditional paper formats are still widely used in Taiwan and China, particularly in educational and promotional products.

8K provides a larger layout suitable for drawing or branding space, while 16K is affordable and convenient for everyday note-taking.

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🧵 Customizing Any Paper Size with Leatai

At Leatai, we specialize in OEM notebook and planner production in all global and regional paper sizes.

✅ Our services include:

• FSC-certified, fountain-pen-friendly paper

• Custom cover printing, foil stamping, debossing

• Binding options: sewn, saddle-stitch, glued, or spiral

• Sizes: A4, A5, B5, 8K, 16K, 32K, Letter, custom

• Low MOQ starting from 500 pcs

When to Convert Paper Sizes? Addressing Common Questions with a Paper Size FAQ

Here is a detailed comparison and conversion chart for various paper sizes. Given the multitude of size specifications, it’s natural to have some questions, so we’ve compiled a couple of FAQs to help clarify any confusion:

📌What is 4「K」、8「K」？

Generally, ‘K’ refers to how many sheets can be cut from a full sheet of paper. For example, an A5 size (25K) means that 25 sheets can be made from a full sheet measuring 31″ x 43″. If converted to Kikuban size, only 16 sheets can be made from a full sheet measuring 25″ x 35″; hence, it is called G16K.

📌With so many paper size specifications, which one should I discuss with manufacturers when producing products?

As each specification results in different full sheet sizes and there are also different standards like the US and Japanese regulations, discussing paper sizes with others can lead to misunderstandings due to the use of various standards. Therefore, when talking about with others or manufacturers, it is recommended to use centimeters to avoid confusion.

📌What is the size of a full sheet?

In the commonly used Taiwan Shiroku Ban, a full sheet is approximately 78.7 cm x 109.2 cm, 31″ x 43″.
For the commonly used Taiwan Kikuban, a full sheet is approximately 63.5 cm x 88.9 cm, 25″ x 35″.

📌What is A5 paper size in inches?

A5 paper measures 5.8 x 8.3 inches (14.8 x 21 cm). It’s compact and ideal for personal notebooks and planners.

📌What’s the difference between A5 and B5?

B5 is larger than A5, offering more writing space, while A5 is more portable.

📌Is A4 the same as Letter size?

No. A4 is 8.3 x 11.7 inches, while Letter size is 8.5 x 11 inches—wider but shorter.

📌What is 8K paper used for?

8K is commonly used for sketchbooks, calligraphy books, and display notebooks due to its large size.

📌What is 16K paper used for?

16K is popular in East Asian markets for student exercise books and small-format journals.

📌Can I order custom notebooks in 8K, 16K, or B5 sizes?

Absolutely! Leatai offers full OEM/ODM notebook production in all standard and custom sizes.

 

Do you now have a better understanding of the various paper sizes? If you want to know which sizes are most commonly used for the planner you typically use, I recommend referring to Leatai‘s planner size guide. It will provide more detailed information about paper sizes and other related insights!

For more information：Leatai | Premium Custom Notebooks & Business Planners from Taiwan
More customization examples： Customized notebooks