How to Convert Between ISBN-10, ISBN-13, EAN, and UPC
Publishers, booksellers, and librarians run into the same friction constantly: a catalog full of ISBN-10s when a retailer demands ISBN-13, or a distributor feed of EANs that needs reconciling against older records. ISBN conversion comes up whenever book data moves between systems built in different eras or for different markets. Understanding the relationship between these formats is what makes the conversion reliable.
The formats
ISBN-10
- 10 digits, used for books published before 2007.
- Uses a modulo-11 check digit. The last character can be "X" (representing ten).
- Being phased out in favor of ISBN-13, but still common in older catalogs and library systems.
ISBN-13
- 13 digits, introduced in 2007 as the global standard. Allows for far more unique identifiers than ISBN-10, eliminating the risk of duplicates across international publishers.
- Always starts with 978 or 979. The 978 prefix maps directly to ISBN-10; the 979 prefix has no ISBN-10 equivalent.
- Uses a modulo-10 check digit, shared with the EAN-13 barcode standard.
EAN (European Article Number)
- A broad retail barcode system covering all product types, not just books. Can be 8 or 13 digits.
- ISBN-13 is a subset of EAN-13: the barcode on the back of any book is an EAN-13, and the number it encodes is the ISBN-13.
- Widely used by distributors, retailers, and fulfillment systems globally.
UPC (Universal Product Code)
- Primarily used in North America, typically 12 digits.
- A UPC-A converts to EAN-13 by prepending a leading zero. Retail scanners in North America can read both formats interchangeably.
- Commonly found on physical products, including books sold through North American retail channels.
How the conversion works
The most common conversion is between ISBN-10 and ISBN-13, and the mechanics are clean because ISBN-13 was designed to embed ISBN-10. To convert ISBN-10 to ISBN-13, drop the check digit, prepend "978", then calculate a new check digit using the EAN-13 modulo-10 algorithm (alternating weights of 1 and 3 across the first twelve digits). Going the other direction strips the "978" prefix and check digit, leaving nine digits, then recalculates a check digit using modulo-11.
The one hard limit: this only works for 978-prefix ISBNs. The 979 prefix was introduced when the 978 address space began running low, and books with 979-prefix ISBNs have no ISBN-10 equivalent. Attempting to convert one produces a meaningless number. Converters that blindly strip the prefix can silently return wrong results for newer titles. ISBNConverter.com detects 979-prefix codes and passes them through unchanged, so your output is never corrupted by a conversion that cannot be done correctly.
EAN-to-UPC conversion is more situational. A UPC-A becomes an EAN-13 with a leading zero prepended, but whether a specific distributor or retailer accepts that EAN in place of a UPC depends on their catalog requirements. The algorithm is simple; the compatibility question is not always.
In practice, most conversion needs come down to ISBN-10 to ISBN-13 conversion (and ISBN-13 back to ISBN-10): older library exports meeting newer retailer requirements. The 978-prefix mapping is lossless for any book published before 2007. For newer titles involving 979-prefix ISBNs, always verify the output rather than assuming a straight conversion is valid.
Frequently Asked Questions
What formats does ISBNConverter.com support?
ISBNConverter.com converts between ISBN-10, ISBN-13, EAN-13, and UPC-A: the four identifiers most commonly used in publishing and retail. Enter any format; the converter detects the type automatically and returns all applicable equivalents. ISBN-13 codes with a "978" prefix have a valid ISBN-10 equivalent. Codes with a "979" prefix are outside the addressable range of ISBN-10 and are returned unchanged.
Who should use ISBNConverter.com?
ISBNConverter.com is built for publishers updating catalogues from ISBN-10 to ISBN-13, librarians reconciling book records across database formats, booksellers preparing inventory exports for platforms that require a specific identifier format, and developers integrating ISBN handling into publishing systems. For individual lookups, use the single converter on this page. For batch work, the bulk converter and file upload tools handle hundreds or thousands of codes at once.
What is the difference between an ISBN and an EAN?
An ISBN (International Standard Book Number) is a subset of the EAN (European Article Number) system, designed exclusively for books. All ISBN-13s are EAN-13s with a "978" or "979" prefix. The EAN system covers all retail products; ISBN covers books specifically. When a retailer scans a book's barcode, they are reading an EAN-13 that happens also to be an ISBN-13. The two are technically identical in 13-digit form; the context of use is what differs.
What happens if I enter an invalid ISBN?
Invalid inputs (wrong digit count, failed checksum validation, or unrecognised formats) return an error message and are not converted. The converter validates the checksum before converting, so any successful result is a verified, correct conversion. If a valid-looking ISBN is rejected, check for extra spaces, dashes, or non-numeric characters that may be interfering with detection.