ISBN Lookup

About this tool

An ISBN lookup that does one thing: you give it the number printed on a book, it gives you the book. Title and subtitle, author, publisher, publication date, page count, cover image, subjects, and the Library of Congress or Dewey call number when the record has one.

The ISBN is checked in your browser before anything is sent, so a mistyped digit gets a clear message instead of a "not found". Both ISBN-10 and ISBN-13 work, with or without hyphens.

It is free, there is no signup, and the only thing that leaves your browser is the ISBN itself, sent to Open Library to fetch the record.

How it works

First the tool strips hyphens and spaces and checks the length: an ISBN has 10 or 13 characters. Then it checks the last character, the check digit, which is calculated from all the others. For an ISBN-13 the digits are weighted 1, 3, 1, 3 and so on; for an ISBN-10 they are weighted 10 down to 2 and the check can be the letter X, standing for 10. If the check digit does not match, the tool says what it should be.

A valid ISBN-10 is converted to its ISBN-13 (and the reverse for 978 numbers), and both are sent to Open Library in a single request. Older books are sometimes catalogued under only one form, so asking for both finds more of them.

Open Library is a free catalogue run by the Internet Archive with records for tens of millions of editions. Its data is contributed and edited by librarians and readers, so coverage is wide but not perfect.

Where to find a book's ISBN

• The back cover barcode. The number printed above the barcode on most books since the 1970s is the ISBN-13. The barcode encodes exactly that number, which is why a phone can read it.
• The copyright page. On the reverse of the title page, often listing separate ISBNs for the hardback, paperback and ebook editions. Use the one for the copy in your hand.
• The spine or dust jacket. Some publishers print it on the jacket flap or the bottom of the spine.

Books from before about 1970 often have no ISBN at all; the system did not exist yet. A number starting 979 is still a valid ISBN-13, it simply has no ISBN-10 equivalent.

What people use it for

• Checking an edition before buying second-hand: page count and publisher tell a reissue from a first printing faster than the cover does.
• Filling in a reading log or library list without typing titles by hand.
• Finding a call number to shelve a classroom or small library in a sensible order.
• Listing books for sale, where the exact title, author and edition matter to buyers.

If you find yourself looking up book after book, that is the point where a scanner beats a search box. Codexia reads the barcode with your phone camera and builds the catalogue as you go.

Frequently asked questions