ISBN Validator - Free, Instant, In Your Browser
Paste a 10 or 13 character ISBN below (dashes optional) to check its checksum.
How to use ISBN Validator
- 1Paste your text or data into the input box above.
- 2ISBN Validator runs instantly, right in your browser.
- 3Copy the result or use it directly.
Your file is processed in your browser and is never uploaded.
Frequently Asked Questions
What's the formula?
ISBN-10 weights each digit 10 down to 1; ISBN-13 alternates weights of 1 and 3 - both must sum to a multiple of 11 or 10 respectively.
Is my data sent to a server?
No - everything runs entirely in your browser with JavaScript. Nothing is uploaded.