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ISBN Converter & Validator

Convert ISBN-10 to ISBN-13 and back — instantly. Free, no signup.

Accepts ISBN-10, ISBN-13, with or without hyphens or spaces.
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ISBN-13 is the standard since 2007. Amazon, KDP and most retailers use it. KDP gives you a free ISBN — you only need your own if you distribute wide via IngramSpark.

How ISBN Conversion Works

ISBN-10 → ISBN-13: Add 978 to the front, drop the old check digit, recalculate a new check digit with the ISBN-13 algorithm.

ISBN-13 → ISBN-10: Remove the 978 prefix and first digit, then recalculate the check digit with the ISBN-10 algorithm.

Check digit: The last digit validates the whole number. If it's wrong, the ISBN is invalid and retailers will reject it.

FAQ

Do I need my own ISBN for KDP? No — KDP provides a free ISBN for Amazon sales. You only need your own for wide distribution.

What does 978 vs 979 mean? Both are valid EAN prefixes for ISBN-13. 978 is more common; 979 is used for some publishers.

Is this converter free? Yes — completely free, no signup, runs entirely in your browser.

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