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ISBN Lookup: The Complete Search Guide

International Standard Book Numbers (ISBNs) are important because they uniquely identify books, and there are a variety of reasons why you might need to search by ISBN. Here, we demystify what ISBNs are, why they’re needed and how to perform an ISBN lookup.

How to lookup an ISBN

Just looking for a quick way to find a book’s ISBN or to lookup books by ISBN? Follow these tips.

Where to find the ISBN on a book

Every modern book is issued an ISBN. You can find it on the book’s barcode, typically located on the back cover.

ISBN on barcode

It can also be found on the copyright page.

ISBN on copyright page

How to find books by ISBN

If you need to find books by ISBN (like when you have a list of books you need to buy for college), you can use an ISBN search engine like Direct Textbook.

Visit our homepage and enter your ISBN into the search box…

DT home

We’ll show you the book’s ISBN, plus additional information like the title, author, publication year, publisher, format, description, reviews and study aids.


You can also compare prices for the books you need in just about any format: new, used, rentals, ebooks and even instructor and international editions.



Why would I need to look up an ISBN?

ISBN lookups can help you:

  • Find the exact book you need (for college or otherwise) and make apples-to-apples price comparisons
  • Find the value of a book you own or wish to sell, whether you’re an individual seller, book collector, appraiser or a book reseller who flips bookstore and garage sale finds (professionals often use ISBN scanners to quickly find values)
  • Order or maintain inventory for libraries, retail bookstores, wholesalers and distributors
  • Find homework answers by textbook
  • Find course materials associated with a textbook
  • Find free PDFS by ISBN
  • Find additional information about a book: title, author, edition, publication date, publisher and imprint
  • Find the ISBN of a book via a search by title, edition and other parameters
  • Create proper book citations for essays, research papers and other documents (for example, APA and MLA citations)
  • Research APIs for application developers who want to automate ISBN lookups (inventory software and scanning systems are examples)
  • Convert ISBNs to and from other identification formats, such as ISSNs and ASINs

What does an ISBN tell you?

An ISBN is a 10-digit or 13-digit code that identifies a specific book by title, edition and format. Each edition and format has its own unique ISBN. For example:

  • The first edition of a textbook will have a different ISBN than the second edition
  • The hardcover format of a novel will have a different ISBN than the paperback format, even if it is the same edition
  • The ePUB, PDF and Kindle versions of a book will all have different ISBNs

ISBNs have either four (10-digit) or five (13-digit) parts, separated by a hyphen or space. Each part helps identify the book:

  • Part 1 (13-digit ISBNs only): The first three numbers of a 13-digit ISBN are always 978 or 979, which tell you you’re reading an ISBN (as opposed to some other type of identifying number)
  • Part 2: Country or language group (also known as the registration group)
  • Part 3: Publisher code
  • Part 4: Book title, format and edition
  • Part 5: The final number is known as a check digit. It is automatically calculated from the previous numbers and helps prevent inventory identification errors. Note that the check digit is a single number (1-9) and the letter X is used to denote the number 10

ISBN meaning

Here’s a breakdown for the ISBN 978-0-321-91029-5, which identifies the fifth edition of Introductory Chemistry, a popular college textbook.

  • The first three digits (978) tell you it’s an ISBN
  • The next digit (0) tells you the book was published in an English language area (Wikipedia has a list of registration groups)
  • The next part (321) tells you the book publisher is Pearson. English language publisher codes are divided into two groups, Group 0 and Group 1. You can match codes to publishers on their respective Wikipedia pages (Group 0 | Group 1)
  • The next part (91029) uniquely identifies the book’s title, edition and format
  • The final number (5) is the check digit

What is the difference between a 10-digit and a 13-digit ISBN?

A 13-digit ISBN begins with a three-digit prefix that identifies it as an ISBN number (as opposed to some other type of number). The U.S. ISBN Agency (administered by Bowker) began adding the 978 prefix in 2007. Prior to that, ISBNs were 10 digits.

Every 10-digit ISBN has a 13-digit equivalent, which means books published with a 10-digit ISBN also have a 13-digit ISBN.

In 2020, the U.S. ISBN Agency added the 979 prefix in response to dwindling inventory for the 978 prefix. Books published with the 979 prefix do not have 10-digit equivalents.

What types of publications are assigned ISBNs?

In addition to physical books, ISBNs are assigned to:

  • eBooks
  • Audiobooks
  • Brochures
  • Coloring books
  • Graphic novels
  • Some historical documents
  • Maps
  • Some educational software

ISBNs are not assigned to periodicals or serialized publications like newspapers, magazines and comic books; and they are not assigned to sheet music, email newsletters, music CDS or movie DVDs. Some CDs and DVDs are eligible for ISBNs if they feature educational content, but you can’t use an ISBN to look up a movie or song.

Find a complete list of publications eligible for ISBNs here.

For students

How do I find textbook availability and compare prices by ISBN?

You can use our free service, Direct Textbook, to instantly see which stores have the books you need and to compare prices in any format: new, used, rental, ebook and even alternative editions.

How can I find additional course materials and study aids by ISBN?

Some colleges make it easy to find course materials via ISBN search. Contact your school to see if they offer this feature on their website.

You can use Direct Textbook to find textbook study aids. Search by ISBN, then click or tap the “Study Aids” link to discover supplemental learning resources.

Can I use a book’s ISBN to look up homework answers?

Yes. Websites like Slader, Bartleby and Chegg Study make it easy to find textbook solutions. Search by ISBN, and these sites will display available solutions for your textbook.

Can I use an ISBN to find free PDF books?

Yes. Websites like PDF Search Engine and Library Genesis (LibGen) allow you to enter an ISBN and find free PDF versions of books. Keep in mind that using free PDF textbooks could infringe on publisher copyrights and invite legal issues. In addition, PDF downloads can come with viruses and malware.

Can I use an ISBN to get MLA and APA citations for essays and research papers?

Yes. You can use free services like BibGuru and OttoBib to automatically cite by ISBN in a number of formats, including MLA, APA and Chicago styles.

How can I find the ISBN for a book by title?

If the ISBN is missing from your book (like if the cover is torn off), you can use Direct Textbook to search for the book’s title. Select your book from the search results to see its ISBN.

For authors

Who assigns ISBNs and how do I get one?

Each country has its own ISBN agency. In the United States, Bowker administers and assigns ISBNs. Self-publishers can apply for an ISBN directly through Bowker or get an ISBN through self-publishing platforms like Amazon (Kindle Direct Publishing).

How much does it cost to get an ISBN and how long does it take?

A single ISBN at Bowker costs $125. A block of ten ISBNs to cover all book formats costs $295, or $29.50 per ISBN.

Some self-publishing platforms (like Amazon and BookBaby) issue ISBNs for free or at discounted prices, but it’s important to note you’ll be limited to selling your book through those services.

If you buy your ISBN from Bowker, you’ll have the freedom to sell it on any platform. The process takes anywhere from 24 hours to 5 days, depending on whether you select express, priority or non-priority processing.

Do ISBNs expire?

No, ISBNs do not expire.

How do I make sure my ISBN is available to bookstores, libraries and wholesalers?

If you use Bowker to register your ISBN, it will automatically be added to the Books In Print database (the process takes a few business days). Libraries, bookstores and wholesalers use the database to find books.

Read Also: How to Get Cheap Textbooks: 2021 Guide


Other FAQs

How do you convert a 10-digit ISBN to a 13-digit ISBN?

Except for the prefix, most of the numbers in a book’s 10-digit and 13-digit ISBNs are identical.

However, the check digit (the last number) means you can’t simply add 978 to convert a 10-digit ISBN to a 13-digit ISBN. That’s because the check digit is created by an algorithm that uses the preceding numbers, so the additional three numbers in a 13-digit ISBN change the check digit.

You can use the free ISBN conversion tool at ISBN.org to convert a 10-digit ISBN to a 13-digit ISBN, and vice versa. The conversion only works for ISBNs with a 978 prefix; there is no 10-digit equivalent for ISBNs with a 979 prefix.

Where can developers find ISBN search APIs?

You can start by learning about APIs offered by Bowker, ISBNdb, Open Library and Google Books.

Is it possible to convert ASINs to ISBNs?

ASIN stands for Amazon Standard Identification Number, and it’s used to identify products in the Amazon ecosystem. You can look up and convert ASINs to ISBNs (and vice versa) via free services like the one found on Synocentric.

What is the difference between an ISBN and an ISSN?

ISBNs are for one-time publications like books, while ISSNs (International Standard Serial Numbers) are for periodicals or serialized publications like magazines, newspapers and trade journals.

What if my book doesn’t have an ISBN?

The ISBN system was adopted in 1967 and formalized in the 1970s, which means books published prior to that do not have ISBNs. Book collectors and appraisers use other clues to identify books and their values, such as the title, author, edition, binding and publication date.

Learn more about how to find the value of a book without an ISBN.