Convert an ISBN
Hyphens and spaces are automatically stripped
Bulk Convert ISBNs
Supports a mix of ISBN-10 and ISBN-13. Each will be converted to the other format.
Convert between ISBN-10 and ISBN-13 formats instantly. Validate check digits and convert in bulk.
An International Standard Book Number is a unique numeric identifier assigned to every published book. It allows publishers, bookstores, libraries, and online retailers to identify any book unambiguously. Every edition and variation of a book (hardcover, paperback, ebook) receives its own ISBN. The system is managed globally by the International ISBN Agency and issued through national agencies in each country.
The original ISBN format used 10 digits and was the global standard from 1970 until 2007. As the publishing industry grew, the numbering space became insufficient. In January 2007, the system transitioned to 13-digit ISBNs, which align with the EAN-13 barcode standard used worldwide in retail. All ISBNs issued today are 13 digits. Existing ISBN-10 numbers with the 978 prefix can still be converted to ISBN-13 and vice versa, but newer 979-prefix ISBN-13 numbers have no ISBN-10 equivalent.
Both ISBN-10 and ISBN-13 include a final check digit that catches common transcription errors. For ISBN-10, each digit is multiplied by a weight from 10 down to 2, the products are summed, and the check digit makes the total divisible by 11. This is why the check digit can sometimes be "X" (representing 10). For ISBN-13, alternating weights of 1 and 3 are used, and the check digit makes the total divisible by 10. A single transposed or mistyped digit will almost always produce a wrong check digit, flagging the error.
An ISBN-13 is divided into five parts: the EAN prefix (978 or 979), the registration group (identifying the country or language), the registrant (the publisher), the publication (the specific title/edition), and the check digit. The hyphenation of an ISBN indicates these boundaries, though the digit count in each segment varies by country and publisher size. For example, large publishers receive shorter registrant codes, giving them more publication numbers.
Conversion between ISBN-10 and ISBN-13 is commonly needed when working with older book databases that still use ISBN-10, importing catalog data between systems, matching books across different retail platforms, or updating library records. Some platforms like Amazon still accept both formats but may store one internally. Academic citation systems may require a specific format. This converter handles both directions and validates the check digit to catch any typos in your source data.
ISBN-10 is the older 10-digit format used before 2007. ISBN-13 is the current 13-digit format that starts with 978 or 979. ISBN-13 was introduced to expand the numbering capacity and align with the EAN-13 barcode system. All new ISBNs issued today are ISBN-13.
No. Only ISBN-13 numbers that start with the prefix 978 can be converted to ISBN-10. ISBN-13 numbers starting with 979 have no ISBN-10 equivalent because the ISBN-10 system did not include the 979 prefix range.
Multiply each of the first 9 digits by its position weight (10 down to 2), sum the products, take modulo 11, and subtract from 11. If the result is 10, the check digit is X; if 11, it is 0.
Multiply each of the first 12 digits alternately by 1 and 3, sum all products, take modulo 10, and subtract from 10. If the result is 10, the check digit is 0.
An invalid ISBN means the check digit does not match the calculated value, or the number has the wrong length. This usually indicates a typo. The converter will show you what the correct check digit should be so you can identify and fix the error.