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ISBN Validator

ISBN Validator is part of Toolspire and is ready as soon as this page loads. Hyphens and spaces are ignored. ISBN-10 is not accepted. The page does not look up whether a publisher issued the number.

Runs in this tabFreeNo account

On this page

What you can do here

The famous example

978-0-306-40615-7 is the number used in the ISBN documentation.

Hyphens ignored

You can paste the printed form.

No catalogue lookup

A valid check digit can still be an unused number.

The sequence

How to use the ISBN Validator

  1. 1

    Paste 13 digits

    The sample should read Valid.

  2. 2

    Change the last digit to 8

    It should read Invalid, and the detail should still say the computed digit is 7.

  3. 3

    Do not paste an ISBN-10

    Ten digits are rejected.

Worth knowing

  • ISBN Validator on Toolspire: 9780306406157 is a valid ISBN-13. The check digit is 7.
  • Weights alternate 1, 3, 1, 3 across the first 12 digits.
  • The check digit is chosen so the weighted sum, including the check digit times 1, is a multiple of 10.
  • Changing any one digit of the sample makes it invalid.

A weighted sum that must end in zero

ISBN-13 multiplies the digits by 1 and 3 alternately, adds them, and demands a multiple of 10. For 978030640615 the weighted sum of the first 12 digits leaves a remainder that the final 7 cancels. The page recomputes that digit and compares it with the one you typed. A match does not mean a library holds the book.

FAQ

Questions about ISBN Validator

Where does ISBN Validator run?

ISBN Validator runs in this tab on Toolspire. What you type or drop in is not sent to us and is not stored on a server.

Is 9780306406157 valid?

Yes.

What if I change the last digit?

It becomes invalid. The computed check digit is still 7.

Are hyphens allowed?

Yes. They are removed before the sum.

Does a valid number mean the book exists?

No. Only the check digit was tested.

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