How to use ISBN Validator
Enter one value in ISBN candidate, or paste several into ISBN candidates. The page removes spaces and hyphens before checking the length, allowed characters, prefix, and checksum. A valid ISBN-10 also gets a converted ISBN-13 in the result.
- Choose Single Candidate or Bulk Candidates.
- Enter one value in ISBN candidate, or paste values into ISBN candidates.
- Separate bulk values with commas or put one candidate on each line.
- Read the status, check rows, and reasons in the validation result.
- For a bulk list, choose Copy CSV or Download CSV when results appear.
What ISBN Validator checks
After spaces and hyphens are removed, the remaining character count selects the form. Ten characters select ISBN-10 checks, and 13 characters select ISBN-13 checks. Any other length produces an unrecognized form and a length reason.
- ISBN-10 requires nine digits followed by a digit or a final
X. - ISBN-10 uses a modulus-11 checksum.
- ISBN-13 requires digits only and must start with
978or979. - ISBN-13 uses a modulus-10 checksum.
A single result lists Normalized candidate, Length (separators removed), Detected form, Allowed characters, Structure valid, Prefix valid (ISBN-13 only), and Checksum. Failed checks include a reason such as the invalid length, character rule, prefix, or checksum.
How ISBN-10 and ISBN-13 input is checked
Spaces and hyphens are removed before the value is checked. This ISBN-10 keeps its conversion after the hyphens are removed:
Input: 0-306-40615-2
Normalized candidate: 0306406152
Detected form: ISBN-10
Checksum: Passes
Converted ISBN-13: 9780306406157The ISBN-10 conversion appears when the structure and checksum pass. The tool does not convert ISBN-13 back to ISBN-10, and it does not look up a title, publisher, catalog record, or book availability.
Bulk ISBN validation and CSV results
Bulk Candidates accepts one candidate per line or comma-separated values. Blank entries are skipped. Each row shows the normalized ISBN, form, length, status, converted ISBN-13 when available, and reasons. The CSV adds Prefix OK and Checksum OK columns, and Download CSV saves isbn-validation-results.csv.
Empty ISBN candidate input produces no result. Empty ISBN candidates input produces no rows, and both CSV controls stay disabled until results exist. The page code does not send entered ISBNs to a server, so processing stays in the browser.
Using the validation result
For one value, check the normalized candidate and each row in the validation result. A valid ISBN-10 includes the converted ISBN-13, while a failed check includes the reason that needs review.
For a list, scan the per-record status and reasons before copying or downloading the CSV. Entries with a length other than 10 or 13 remain unrecognized, so they do not receive an ISBN form or conversion.
Choosing another data validator
Use Data Validation Tools for another identifier. An IBAN Validator checks country-specific bank account structure and MOD-97 values. A Credit Card Validator checks card-number length, network prefixes, and Luhn values. For encoded text, use a Base64 Validator to inspect padding and variant details.
Frequently asked questions
How do I validate an ISBN in bulk?
Choose Bulk Candidates and paste one ISBN per line or separate candidates with commas. Review each row, then choose Copy CSV or Download CSV.
Can I validate an ISBN-10 and convert it to ISBN-13?
Yes. A valid ISBN-10 receives an ISBN-13 conversion in the result. The conversion uses the first nine ISBN-10 digits, adds the 978 prefix, and recalculates the check digit.
What does an invalid ISBN mean?
An invalid ISBN fails one or more structure, allowed-character, prefix, or checksum checks. The result lists the applicable reason. It does not identify the book or confirm a catalog record.
Does the ISBN Validator upload my ISBNs?
No. The entered values are processed in the browser, and this page code does not transmit them to a server.