What is the ISBN of a Book?

What is the ISBN of a Book

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ISBN stands for International Standard Book Number. It is a unique 10- or 13-digit number separated by spaces or hyphens. ISBN is assigned to every book that is published to be sold commercially.

What is an ISBN Used For?

ISBN is used as a product identifier by publishers, booksellers, internet retailers, libraries, distributors, and other supply chain participants to order, list, record sales, and track the inventory of a book. ISBN also contains essential information about the book, such as its registrant, title, edition, and format.

Two points on uses of ISBN
Importance of ISBN

Why is ISBN Important?

ISBNs are the only book identifier that is internationally recognized. They allow books to be catalogued and tracked throughout the entire supply chain, from publishers to retailers.

Moreover, ISBN makes it possible for consumers to identify and purchase the exact book no matter where they are in the world.

How to Get an ISBN as a Self-Published Author?

How to get ISBN as a self-published author

There are two ways to get an ISBN as a self-published author.

  1. Purchase an ISBN directly from the official website of the ISBN agency in your country.
  2. Use a self-publishing platform that provides ISBN as part of their publishing package.


Once you purchase the ISBN or your publishing agency gives you one, you must furnish the following information to complete the process.

  • Book title
  • Book subtitle (optional)
  • Book description (optional)
  • Cover image of the book (optional)
  • Book’s medium (e.g., audio, e-book, print)
  • Book’s format (e.g., paperback, hardcover)
  • Subjects and genres
  • Details about authors and contributors (details include name and biography)
  • Sales and pricing information (includes publication date, title status, target audience, and book price)

ISBN Providers / Agencies

ISBN providers/agencies play a significant role in the book publishing industry. These organizations are responsible for assigning ISBNs and maintaining the database of all ISBN-registered books.

Here is a list of some popular ISBN providers/agencies worldwide.

List of Popular ISBN Providers/Agencies Worldwide
United States
United Kingdom
Canadian ISBN Agency
ISBN-Agentur Bundesrepublik Deutschland
Agencia del ISBN
Japan Publishing Organization
Raja Rammohun Roy Agency

Self-Publishing Platforms

Apart from purchasing ISBNs, you can get them for free by using a self-publishing platform. These platforms provide ISBNs as part of their publishing package. Getting ISBNs from self-publishing platforms is a convenient option if you are new to the publishing world and are on a tight budget.

Some of the popular self-publishing platforms that offer free ISBNs are.

Popular Self-Publishing Platforms That Offer Free ISBNs
Amazon KDP
Free ISBN for any book (except low content books)
Free ISBN included in service
Free ISBN included in service
Free ISBN included in service
Free ISBN included in service

Drawbacks of Free ISBNs

Seven points on drawbacks of free ISBNs

The major drawback of using a free ISBN is that you will not have full control over the book’s metadata.

Free ISBNs do not list your original publisher of the book. Instead, it will list the printing service or distributor that gave you the free ISBN as a publisher.

As a result, it will make your book difficult to find since its publisher is not listed in book directories. Moreover, you will not be able to build up your own publishing brand.

Other drawbacks of free ISBNs are.

  • Free ISBNs are non-transferable. This means if you ever decide to switch book publishing service providers, you have to get a new ISBN. Additionally, if you acquire a free ISBN from a website like Amazon, you cannot use it with another retailer.
  • They do not have an EIN-5 barcode that gives the book’s price information. EIN-5 is required by most bookstores, and not having one will limit where you can sell your book.
  • Some stores will not sell your books if you take a free ISBN from platforms like Amazon. 
  • Free ISBNs may expire or deactivate without notice.
  • Free ISBNs may not be unique to your book. This means another book can have the same ISBN as yours, confusing consumers and retailers.

Is an ISBN Necessary to Publish a Book?

List of six points on why an ISBN is necessary to have

ISBN is necessary for every printed book that is intended to be sold commercially or distributed to libraries. However, if the book is in another medium, such as audio or e-book, then ISBN is not mandatory.

Here are some situations where getting an ISBN is essential.

  • If you wish to sell your book online or through brick-and-mortar stores.
  • If you want to submit your book to libraries.
  • If you want to make your book more discoverable and accessible to potential readers.
  • ISBNs (along with barcodes) give credibility to your book.
  • If you want to have more control over the metadata associated with your book.
  • It enables more efficient distribution of your title.
  • If you want to benefit from public lending rights as most countries use ISBN to identify the number of times public libraries lend out a book. 

How Much Does an ISBN Cost?

The cost of an ISBN varies depending on your country and the number of ISBNs you purchase. 

In the United States, Bowker, the official ISBN agency, offers a single ISBN for $125 and a block of 10 ISBNs for $295.

In the United Kingdom and Ireland, Nielsen, the official ISBN agency, offers a single ISBN for £91 and a block of 10 ISBNs for £169.

In Canada, ISBNs are free for Canadian publishers and can be obtained via the ISBN Canada online system

How do I Find the ISBN Number of a Book?

The ISBN number of a book is found in two places.

  1. On the back cover just above the bar code.
  2. On the copyright and publisher information page of the book.

You can also enter the book title or author name into numerous online ISBN search engines such as isbnsearch.org to find the ISBN and other information like book price.

location of ISBNs in the book

How Many Numbers Should an ISBN Have?

According to the International ISBN Agency, an ISBN should have 13 numeric digits.

However, before 2007 ISBNs were only ten digits long.

To accommodate the growing global book industry, the International ISBN Agency expanded the number of digits from 10 to 13 starting on 1 January 2007. 

Therefore, if you have a book published before 2007, it will have a 10-digit ISBN, and if the book were published after 2006, it would have a 13-digit ISBN. 

ISBN-10 Vs ISBN-13 - The Difference

Difference between ISBN-10 AND ISBN-13

Here is a table that shows the key differences between ISBN-10 and ISBN-13. 

It has 10 numeric digits.
It has 13 numeric digits.
It has four sections, namely, group identifier, publisher identifier, title identifier, and check digit.
It has five sections, namely, prefix element, registration group element, registrant element, publication element and check digit.
Prefix Element
It does not has a prefix element.
It has a 3-digit prefix that can only be either 978 or 979.

How to Convert ISBN-10 to ISBN-13?

Here is a 6-step guide on converting ISBN-10 to ISBN-13. 

  1. Step 1 – Remove the final digit, also known as the “check digit,” of the ISBN-10 number. 
  2. Step 2 – Add the prefix digit to the remaining nine digits of ISBN-10. Put 978 if the book was published in an English-speaking region outside the United States. Prefix 979 if the book is published in the United States and its associated territories.
  3. Step 3 – Take the 12 digits from Step 2 and multiply each digit with 1 and 3 alternately. In other words, multiply the first digit by 1, the second digit by 3, the third digit by 1, the fourth digit by 3, and so on. Keep doing this until you have multiplied each of the 12 digits from Step 2.
  4. Step 4 – Add all the answers from Step 3. Now perform a modulo 10 division. You can use this modulo calculator. Please note down the remainder, as that is what we need for the next step.
  5. Step 5 – Check digit calculation. If the remainder from Step 4 equals 0, then 0 is the check digit. If the remainder is not equal to zero, subtract the remainder from 10 to get the check digit.
  6. Step 6 – Put the check digit at the end of the 12 digits from Step 2. Congratulations, you have successfully converted ISBN-10 to ISBN-13.

Alternatively, you can use Bowker’s online ISBN converter tool to convert ISBN-10 to ISBN-13 and vice versa.

What do the ISBN Numbers Mean?

ISBNs have a unique structure that can be divided into sections depending on their information. Here is an anatomy of a 10-digit and 13-digit ISBN. 

10-Digit ISBN Number

What does ISBN number mean

ISBN-10 has four parts. 

  1. Group Identifier
  2. Publisher Identifier
  3. Title Identifier
  4. Check Digit

Group Identifier

Group identifier identifies the country, geographical region, or language of the area in which the book was published. This part contains one to five digits in length, depending on the number assigned by the International ISBN Agency. 

For example, 0 and 1 are used for English-speaking countries; 976 is used for the Caribbean Community; 61 is used for Brazil. 

Publisher Identifier

The publisher identifier represents the publisher of the book. It is assigned based on the country, geographical area, or language area in which the publisher’s agency is located.

The length of the publisher identifier ranges between one to seven digits.

Title Identifier

Title identifier indicates a specific title, edition, or variation of the book. This part contains one to six digits in length.

Title identifier is also used to lengthen the ISBN to 10 digits, if necessary, by adding preceding zeroes.

Check Digit

A check digit is the final, 10th digit calculated using the first nine digits. It is used to validate and verify the accuracy of an ISBN.

A check digit is any number between 0 to 9. It can also be X which represents 10. 

13-Digit ISBN Number

Five parts of 13-Digit ISBN number

A 13-digit ISBN has five parts.

  1. Prefix Element
  2. Registration Group Element
  3. Registrant Element
  4. Publication Element
  5. Check Digit

Prefix Element

The prefix element is the first three digits of the ISBN-13. Currently, the prefix element is 978 or 979 only.

The prefix element converts ISBN into EAN, which is a universal product code. EAN ensures that the ISBN system is compatible with other global product identification systems that are administered by the EAN system.

The ISBN system received the prefix element from GS1, which is a non-profit organization that creates and maintains barcode standards and prefixes for global trade and commerce.

Registration Group Element

The registration group element identifies the country, geographical region, or language of the area in which the book was published. 

Registration group contains one to five digits in length depending on the number assigned by the International ISBN Agency. For example, 2 is used for the French language, 5 is used for the former USSR, and 84 is used for Spain.

Registrant Element

The registrant element identifies the publisher or imprint of the book. It is assigned by the registration group agency depending on the country, geographical region, or language area in which the registrant’s ISBN agency is located.

The length of the registrant element ranges between one to seven digits.

Publication Element

The publication element represents a particular title, edition, or format of the book. This part contains one to six digits in length.

The publication element is used to lengthen the ISBN to 13 digits, if necessary, by adding preceding zeroes.

Check Digit

The check digit is the last single-digit number that validates and verifies the accuracy of an ISBN. It is mathematically calculated using the first 12 digits.

A check digit can be any number between 0 and 9. It can also be X which represents 10.

ISBN vs Barcode: What's the Difference?

ISBN and barcodes carry the same information but are used for different purposes.

Barcode is a machine-readable code that encodes data with bars and spaces of varying widths. They are a visual method of representing data that can be quickly read and interpreted by scanning machines like a barcode scanner. 

A barcode encodes a book’s ISBN and price, allowing a book to be identified and priced quickly at the point of sale. Barcodes are also used for sales tracking and inventory management of the book. 

Check out our barcode 101 guide to learn about barcodes.

Difference between ISBN and Barcode

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