ISBN-10 vs ISBN-13
An ISBN (International Standard Book Number) identifies one edition of one book. Until the start of 2007 ISBNs had 10 digits. Since then they have 13, matching the EAN barcodes used on retail products, which is why the ISBN-13 is the number printed under a book's barcode.
Every ISBN-10 has an ISBN-13 twin: the same nine core digits with 978 in front and a recalculated check digit. Newer ISBNs that start with 979, including recent US ISBNs beginning 979-8, have no ISBN-10.
How to convert ISBN-10 to ISBN-13 by hand
- Drop the last digit of the ISBN-10.
0-306-40615-2becomes030640615. - Put 978 in front:
978030640615. - Multiply the twelve digits alternately by 1 and 3 and add them up. Here the total is 93.
- The check digit is whatever brings the total up to the next multiple of 10. 93 needs 7, so the ISBN-13 is
978-0-306-40615-7.
Going the other way, remove the 978 and the last digit, then work out a new ISBN-10 check digit: multiply the nine digits by 10, 9, 8 … 2, add them up, and pick the digit (or X for 10) that makes the total a multiple of 11. The converter shows this working for any ISBN you enter.
Why check digits matter
The last digit of every ISBN is calculated from the others, so most typing mistakes, such as one wrong digit or two digits swapped, produce an invalid ISBN. If the converter says the check digit doesn't match, look at the book again before ordering or citing it.
Where to find a book's ISBN
- On the copyright page, usually the back of the title page.
- Under the barcode on the back cover (the ISBN-13).
- On your course syllabus, the campus bookstore listing or the library catalogue record.
Looking for answer keys or worked solutions for a textbook? Our guide to finding textbook solutions and studying with them covers the legitimate options.
Frequently asked questions
What is the difference between ISBN-10 and ISBN-13?
Both identify the same edition of a book. ISBN-10 was the standard until the start of 2007; since then every new ISBN has 13 digits. An ISBN-13 is the ISBN-10 with 978 in front and a new check digit at the end.
Why does my ISBN-13 have no ISBN-10?
ISBN-13s that start with 979 were issued after the switch to 13 digits and never had a 10-digit form. Only ISBNs starting with 978 can be converted to ISBN-10.
What does the X at the end of an ISBN-10 mean?
It stands for 10. The ISBN-10 check digit can be any value from 0 to 10, and X keeps it to a single character.
Is it the same ISBN for the paperback, hardcover and ebook?
No. Each format and each edition has its own ISBN, so check that the ISBN you use matches the exact version your course or library lists.
Does this tool store the ISBNs I enter?
No. Conversion happens in your browser. To show the book's title and cover, the ISBN is looked up in Open Library's public catalogue.