Enter a value and run the local tool.
Method and worked example
Spaces and hyphens are removed. ISBN-10 uses the modulo-11 weighted checksum; ISBN-13 uses alternating 1 and 3 weights. A valid ISBN-10 can be converted by adding 978 and calculating a new checksum.
0-306-40615-2 validates as ISBN-10 and converts to 9780306406157. ISBNs ending in X are handled with X equal to ten.
Scope and limitations
Checksum validity does not verify a book or assignment. Canonical hyphenation is not invented because it requires registration-range data.
Review the output before using it in academic, publishing, or identity workflows.