ISBN-10 to ISBN-13
An ISBN is not just a catalog number: its final digit exists to prove the whole code was typed or printed correctly. This page shows how the check digit is calculated for both ISBN-10 and ISBN-13, and converts a real code from one format to the other, recalculating the digit by hand, before you look one up in the tool.
The weights run from 10 down to 1, left to right, and the sum lands exactly on a multiple of 11, with no remainder.
The 978 prefix switches the algorithm from modulo 11 to modulo 10 with weights of 1 and 3, so the final digit changes too: the correct ISBN-13 ends in 7, not 2.
Changing only the last digit shifts the remainder on division by 11 and invalidates the entire code, even though the other 9 digits are correct.
ISBN stands for International Standard Book Number. It is the identifier of a book edition, used by publishers, bookstores, libraries and online stores for cataloging, sales and stock control. Each edition and each format of the same work should have its own.
Because ISBN-10's modulo 11 can produce a remainder of 10, a value that doesn't fit in a single decimal digit; the standard solves this by allowing the letter X in the check-digit position only.
Books published before the industry moved to the 13-digit standard in 2007 originally only had an ISBN-10, but any ISBN-10 can be mathematically converted to ISBN-13 by prefixing 978 and recalculating the check digit; books released after 2007 are issued with an ISBN-13 from the start.
Prefix (978 or 979 in ISBN-13), registration group (identifies the country or language area), registrant (the publisher), publication number (the specific title), and check digit; the size of each block varies with how much a publisher or country has already registered.
Yes for ISBN-13: it follows the EAN-13 algorithm exactly, so the barcode printed on a book's back cover is the ISBN-13 itself encoded, with no additional conversion.
Open in a new tab. The catalog may not have the book.
Validating, converting, the anatomy view, the barcode and batch processing all happen in your browser. Only the Look up book tab sends the ISBN: to the jkit.tools server, which forwards it to BrasilAPI, and to Open Library. Google Books is only queried if the other two do not find the book.