What is an ISBN?
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What is an ISBN number?
If you see a set of numbers next to a black-and-white barcode on the back cover of the book, you're looking at an ISBN number. The International Standard Book Number, or ISBN, makes it easy to identify any book ever published. This code usually consists of 10 or 13 digits. It helps you find the exact edition of a book. Therefore, a book search by ISBN is essential for buying or selling books.
What does an ISBN identify?
The ISBN (International Standard Book Number) is a unique identifier assigned to each edition of a book. It consists of five elements that are usually separated by spaces or hyphens.
Here’s the ISBN meaning:
- Prefix element is a 3-digit code (currently either 978 or 979) that indicates this exact system being used.
- Registration group (1–5 digits) identifies the specific country, geographical region, or language area.
- Registrant element (up to 7 digits) identifies the particular publisher or imprint responsible for the book.
- Publication element (1–6 digits) distinguishes the specific edition and format.
- Check digit is the final single digit that serves as a mathematical validation of the entire number.
The length of the ISBN can vary depending on the lengths of the above-mentioned elements, but the structured format always remains the same. It’s important as each section plays a role in uniquely identifying a book's edition, publisher, and format, and it ensures accurate identification and tracking of a specific title within the publishing industry.
Important note:
Each book version (hardcover, paperback, eBook) should have its own unique ISBN.
What's the difference between ISBN-10 and ISBN-13?
- Length
- ISBN-10 uses 10 digits (9 digits plus a check digit).
- ISBN-13 uses 13 digits.
- Format
- ISBN-13 starts with the prefix 978 or 979, followed by the re-arranged ISBN-10 digits and a recalculated check digit. For example, ISBN-10 0-323-77671-X becomes ISBN-13 978-0-323-77671-4.
- Check digit calculation
- The check digit in ISBN-10 can be a numeric value from 0–9 or the Roman numeral X.
- In ISBN-13, the check digit is always a single numeric digit.
- Compatibility
- ISBN-13 was introduced in 2007 to avoid the depletion of ISBN-10 numbers and increase compatibility with EAN barcodes used globally.
- All new books are now assigned ISBN-13, but older titles still have their original ISBN-10.
Important note:
To convert a 10-digit into a 13-digit ISBN or vice versa, use the ISBN converter.
Why do some ISBNs end in "Х"?
The “X” at the end of some ISBN-10 numbers is not an error—it is the Roman numeral X and a legitimate check digit value representing 10 in the Modulus 11 calculation. In the newer ISBN-13 format that uses a Modulus 10 calculation, this X is dropped in the process of conversion, resulting in a numeric value between 0–9.
Important note:
eBooks don't require an ISBN, while physical books (hardcovers and paperbacks) do; otherwise, they cannot be sold. However, if you want to sell eBooks in a store, you should check the store’s policy and requirements.
Why do we need an ISBN?
This number is a unique code that identifies a specific edition. Its use facilitates efficient book distribution, sales, and cataloging processes, making sure that publishers, booksellers, libraries, and other stakeholders can communicate and exchange data worldwide. All in all, ISBNs provide a standardized system for the publishing industry ecosystem.
Important note:
An ISBN cannot be reused. Even if a title goes out of print, libraries and booksellers will continue using its ISBN, so reusing will cause confusion.
Who should apply for an ISBN?
Self-published authors
If you are self-publishing a printed book and want to be listed as the official publisher, you should apply for your own ISBN. This gives you control over the book's metadata and rights.
Independent publishers
Small presses, independent publishers, and any entity planning to publish and distribute printed books commercially should obtain their own ISBNs.
Traditional publishers
Major publishing houses must acquire blocks of ISBNs to assign to the various titles and editions they publish.
Important note:
According to the International ISBN Agency, “A widely held belief is that ISBN protects copyright. It doesn’t, it is an identifier and copyright is the author’s.”
Who assigns ISBN numbers?
The International ISBN Agency oversees the administration of unique book numbers globally. However, each country has a designated agency responsible for ISBN management and distribution within its borders.
Important note:
You cannot get an ISBN for books published in the US from the International ISBN Agency.
How to get an ISBN number in the US?
In the US, Bowker is the sole agency authorized to register ISBNs. The official name of the organization is R.R. Bowker, LLC. It’s headquartered in Chatham, New Jersey. They provide an online portal where US publishers can instantly purchase and obtain unique book numbers.
- Go to My Identifiers and create an account.
- Log in and purchase a single ISBN or a bundle.
- Provide the required metadata for each title.
- An ISBN will be assigned to your book instantly through the portal.
In the U.S., registering a single ISBN costs $125. Bundles of 10 numbers can be purchased for $295, 100—for $575, and 1,000—for $1,500.
Important note:
You can check the list of prices for US authors and publishers on the official Bowker website.
Can you get an ISBN for free?
Self-publishing platforms and services
Self-publishing platforms like Amazon KDP, IngramSpark, Lulu, and others provide free ISBNs when you publish your book through their services. However, they often come with limitations and may list the platform as the publisher instead of you.
Some self-publishing companies help authors self-publish their works through print-on-demand services (e.g., Bookbaby, iUniverse, Bookllo Publishing, etc.). They offer a free ISBN with their book publishing package.
National ISBN agencies in certain countries
A few countries like Hungary, Canada, India, Pakistan, and Thailand provide free ISBNs to their citizens through the national ISBN agency.
Important note:
Purchasing your own ISBNs, while more expensive, gives you full control and ownership as the publisher.
Why use barcodes instead of ISBNs?
An ISBN of a book and a bar code are two different things. While the former is a number, the latter is a graphical representation with vertical lines. It contains encoded numerical information for scanning purposes. Barcodes are required to sell print books through major retailers.
Why do books have both? The ISBN serves as a unique book identifier used by many different parties. Barcodes are mostly used by booksellers to manage, purchase, and sell their inventory. There are even online tools that help convert an ISBN into a bar code.
Important note:
You can get a bar code from the agency that provides you with the ISBN. In the US, it’s Bowker. To get a barcode, go to their My Identifiers website.
Where is an ISBN on a book?
- Back cover: Most books have the ISBN printed on the back cover, usually near or within the barcode. If your title goes with a dust jacket, the ISBN and the bar code are usually located on the bottom right corner of the back cover of the jacket.
- Copyright/Publisher information page: If you can’t find the ISBN on the back cover, check its copyright/publisher information page.
Keep in mind, however, that books published before the 1970s do not have an assigned ISBN. Also, since the ISBN format change in 2007, newer items now display the 13-digit ISBN.
If you can’t locate the ISBN on a physical book, checking an online catalog like WorldCat can help you out. Chances are that you’ll find the associated ISBN for your specific title and edition there.
Important note:
Using the accurate ISBN is crucial for identifying, ordering, and tracking editions.
What’s the difference between ISBN and ISSN?
- Purpose:
- ISBN (International Standard Book Number) identifies a distinct publication or edition.
- ISSN (International Standard Serial Number) identifies an entire series of a serial publication, a continuing serial publication like a journal, magazine, or newspaper.
- Structure:
- ISBN is 13 or 10 digits long.
- ISSN is 8 digits long, divided into two groups of 4 digits separated by a hyphen.
- Assignment:
- Each different edition/format gets a unique ISBN.
- All formats/editions of the same serial publication share the same ISSN.
- Publisher:
- The ISBN can identify the specific publisher of a book.
- The ISSN does not identify the publisher of a serial.
- Usage
- ISBNs are mandatory and are used for ordering, inventory management, and sales tracking.
- ISSNs are optional and are used primarily for library cataloging and record-keeping.
- Availability:
- ISBNs must be purchased from an authorized agency.
- ISSNs are assigned for free by the ISSN International Centre.
Important note:
ISSNs are especially helpful in distinguishing between serials that may have the same or similar titles published by different organizations.
How to search books by ISBN?
While you can find a book you need by typing the title and the author in the search field, a search by ISBN will bring you to the exact edition. BooksRun has one search field for purchase, sale, and rent—you just enter the ISBN code, click search, and get transferred to the relevant edition. You can also search by scanning barcodes with the BooksRun app for Android or iOS.
To enter the correct ISBN, check the back cover or the page containing the copyright statement. If you want to look by ISBN-13, enter the 13-digit code that starts with the number 978 or 979. If you’re looking for an older book with ISBN-10, enter the 10-digit code that starts with 0, 1, or 2.
Important note:
Make sure you choose the correct ISBN if the search results show more than one. For example, if you're selling a hardcover, choose the ISBN that says "hardcover” next to it.
How to compare book prices and sell a book using ISBN?
If you want to sell your used book to a bookstore, it's a good idea to compare prices at different places, such as Amazon or eBay, to find the best offer. With BooksRun's search system, you can easily search using the book's ISBN and see all the current price offers. Additionally, you can browse through pages dedicated to particular categories (like Economics or Biology) or a specific course.
Textbook search by ISBN; perks of international and older versions
Searching for textbooks by ISBNs is the fastest and most convenient way to find exactly what you need. As a student, you are given a list of titles each semester, so instead of looking for the textbooks by their titles, use their ISBNs instead. Your list will probably contain all the newest editions (which are usually more expensive than older ones).
Don't rush to buy them all at once; instead, ask your professors if older versions are also suitable for their classes. We recommend searching for the ISBNs of the older editions in advance and discussing them with your teachers. Since prices might notably differ, purchasing older editions instead of costly brand-new ones can allow you to save plenty of money.
Important note:
You can also try using international copies since they're technically the same books.
