About the ISBN Formatter
ISBN lists collect inconsistencies: some with hyphens, some with spaces, some with an "ISBN" label, old 10-digit numbers mixed with 13-digit ones. Before you use them in a catalogue, a spreadsheet, metadata feeds or your back matter, they need to match. This formatter cleans and standardises the whole list at once.
Paste ISBNs one per line, choose hyphenated or digits only output, and the table shows each input, its type, whether it is valid, and its ISBN-13 and ISBN-10 forms. ISBN-10s are converted to ISBN-13 automatically, and 978 ISBN-13s get their ISBN-10 equivalent. Copy the ISBN-13 list or download everything as CSV.
Entries that fail validation are never "fixed" by guessing. A wrong check digit or a missing digit is flagged with the reason, so you can look up the correct number. Hyphenation is exact for the 978-0 and 978-1 groups; other groups, including 979, are shown with the prefix and check digit separated. To inspect a single ISBN in detail, use the ISBN Validator.
How It Works
Each line is cleaned by removing spaces, hyphens, dots and an ISBN label, then validated by length, allowed characters, prefix and check digit.
Valid ISBN-10s are converted to ISBN-13 by adding 978 and recalculating the check digit. Valid 978 ISBN-13s are converted back to ISBN-10. 979 ISBNs have no ISBN-10 form.
In hyphenated mode, the registrant and publication blocks are split using the built-in ranges for 978-0 and 978-1. In digits only mode, no hyphens are added.
Example
A mixed list of five entries
- 9781861972712 becomes 978-1-86197-271-2, with ISBN-10 1-86197-271-7.
- ISBN 0-306-40615-2 is an ISBN-10; its ISBN-13 is 978-0-306-40615-7.
- 9798123456781 is valid and becomes 979-812345678-1, with no ISBN-10 because it starts with 979.
- 978186197271 has only 12 digits, so it is flagged as an error rather than completed.
Four entries are formatted and one is flagged for fixing, with no digits invented.
Important Notes
- Formatting never changes digits. Invalid or incomplete entries stay invalid and show the reason.
- Exact hyphenation is available for the 978-0 and 978-1 groups. Other groups show a prefix-separated form.
- Up to 1,000 entries are processed at a time.
- The CSV is built in your browser. Your list is not uploaded.
Frequently Asked Questions
Should I use hyphens in KDP?
KDP's ISBN field generally takes the number without hyphens. Hyphenated ISBNs are common on copyright pages and in printed catalogues, so choose the style that fits where you are pasting.
Why is a valid ISBN not fully hyphenated?
Hyphen positions depend on agency ranges for each registration group. Only the 978-0 and 978-1 ranges are built in, so other groups show the prefix and check digit separated instead of a guess.
Can it convert ISBN-10 to ISBN-13?
Yes. Every valid ISBN-10 is shown with its ISBN-13, which you can copy as a list or download in the CSV.
What does the CSV contain?
One row per entry: your original input, the type, valid yes or no, the ISBN-13 and ISBN-10 in your chosen style, and the error message for invalid entries.
Why won't it complete my 12-digit ISBN?
Calculating a check digit for 12 digits would produce a well formed number, but not necessarily your number. If a digit is missing, only your assignment record has the correct ISBN.
Related KDP Tools
- ISBN ValidatorValidate ISBN-10 and ISBN-13 check digits and convert between them.
- Book Launch ChecklistAn interactive checklist from manuscript to post-launch, saved in your browser.
- KDP Page Count CalculatorConvert word count to estimated pages, or pages to words, by trim and font size.
- Word Count CalculatorCount words, characters, sentences and paragraphs, with page and reading-time estimates.
- Book Title GeneratorGenerate title ideas from your genre, topic, audience, tone and keywords.
- Book Description FormatterClean up a book description, add headings and bullets, and count characters.