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ISBN-10 Validator

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Values to check

Result

ISBN-10scheme0values0valid0invalid0unreadable

Weights 10 to 1 mod 11. The check character can be X.

Open the full check digit validator with Luhn, IBAN, ISBN, GTIN, VIN, ISIN, Verhoeff, and Damm

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Settings are written to the URL as you change them. Nothing differs from the defaults yet.

Mod 11 and the X character

ISBN-10 weights the digits 10, 9, 8 and so on down to 1, then checks the sum against 11. The larger modulus is what lets it catch transpositions that a mod 10 scheme lets through.

The cost is that one of the eleven possible remainders needs two characters. X is reserved for it, and it only ever appears in the final position.

Hyphens

Hyphens in an ISBN separate the registration group, registrant, and publication elements. They are stripped before the check runs, so 0-306-40615-2 and 0306406152 produce the same verdict.

Every ISBN-10 has an ISBN-13 equivalent that starts with the 978 prefix, and the two carry different check characters. Confirm which one a catalog expects before importing a list.

Frequently Asked Questions

How is an ISBN-10 validated?

The 10 characters are weighted 10 down to 1 and summed. The number is valid when that total is divisible by 11.

Why do some ISBNs end in X?

A mod 11 remainder can be 10, which does not fit in a single digit. The Roman numeral X stands in for it.

Can it convert an ISBN-10 to an ISBN-13?

No. Conversion means prefixing 978 and recomputing the check digit under the GTIN rules, which the ISBN-13 page handles.

Pages locked to one scheme

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