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An ISBN (International Standard Book Number) identifies one edition of a book in one format. On the back cover it’s printed as an EAN-13 barcode that starts with 978 or 979, so any scanner that reads EAN-13 reads ISBNs.

Decode one

Scan or paste a barcode and see every part of it.

Make one

Generate a valid barcode from fields.

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Where you’ll see it

  • Books, usually on the back cover.
  • Each format separately. The hardback, paperback and ebook of one title each have their own ISBN.
  • Not on magazines or journals. Those use an ISSN.

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Anatomy

The barcode is an ordinary EAN-13: 95 modules wide, with the first digit encoded in the pattern of the left half. Only the meaning of the digits is different.

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The five parts of an ISBN

Printed above the barcode, the same number appears with hyphens: ISBN 978-0-306-40615-7. The hyphens separate five parts: Three of the parts vary in length, so you can’t tell where the hyphens go from the digits alone. The barcode has no hyphens. If you need them, you have to look up the ranges the International ISBN Agency publishes.

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ISBN-10 and ISBN-13

ISBNs were 10 digits until the end of 2006 and have been 13 digits since January 1, 2007. Older books still show the 10-digit form above the barcode. To convert an ISBN-10, put 978 in front, drop the old check digit, and calculate a new one. The check digits differ, so you can’t convert by adding 978 alone. Only 978 numbers have a 10-digit form. An ISBN that starts with 979 can’t be written as an ISBN-10.

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The price add-on

Many books carry a second, smaller barcode to the right: a 5-digit add-on that holds the recommended price. The first digit is the currency, and 5 means US dollars, so 51995 is $19.95. 90000 means no price is given. Scanners read the add-on only if they’re set up to.

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Check digit

The last digit of an ISBN-13 is calculated the same way as any EAN-13, with the GS1 mod-10 algorithm: The ISBN-10 check digit uses a different method, mod-11. Both are worked through in Check digits.
  • EAN-13: the barcode an ISBN is printed as.
  • ISSN: the equivalent for magazines and journals, with prefix 977.
  • ISMN: printed music. Its numbers start 979-0, so they look like ISBNs but aren’t.

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Gotchas

  • Hyphens on the cover, none in the scan. See ISBNs and hyphens.
  • 18 digits instead of 13. The price add-on was read too. See an add-on that came along.
  • A 10-digit number from a scanner. Some scanners can convert 978 barcodes back to ISBN-10. Turn that off and store 13 digits.
  • X isn’t a typo. An ISBN-10 check digit of 10 is written X. Don’t strip it or validate ISBN-10s as digits only.
  • Not every 978 or 979 barcode is a book you can look up. 979-0 numbers are sheet music.

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Scanning it in your app

A scanner reports an ISBN as an EAN-13. ISBN is in the Retail product group along with EAN-13, so enabling that group reads books too.
The pattern accepts only 13-digit numbers that start with 978 or 979, so the field rejects other products. See Validation.

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Specification