ISBN-10 Regex Pattern

Validates a 10-character ISBN. Last position can be X (representing 10 in mod-11 checksum).

Pattern
^(?:\d{9}X|\d{10})$

Tested examples

0306406152
080442957X
9780306406157
030640615
030640615Z

Test it live

Live Regex TesterJS
0 matches
/
/g
0306406152
080442957X

Use it in your language

Use it in
// JavaScript / Node.js
const regex = /^(?:\d{9}X|\d{10})$/;
const value = "0306406152";
const isMatch = regex.test(value);
console.log(isMatch); // true / false

// Extract all matches
const matches = value.match(/^(?:\d{9}X|\d{10})$/g) || [];

Tags

Frequently asked questions

How do I use the ISBN-10 regex pattern in JavaScript?
Wrap the pattern in slashes: const re = /^(?:\d{9}X|\d{10})$/; — then call re.test(value) to check a single value, or value.match(re) to find matches. The "Use it in" snippets above give you the exact code for 9 languages.
Is this isbn-10 regex production-ready?
Yes — every pattern in the library is tested against valid and invalid examples. Still, regex is one layer in a defense-in-depth strategy: pair it with server-side validation (e.g. Luhn for credit cards, mod-97 for IBAN, real DNS lookup for emails) for critical inputs.
Why does my pattern fail in another language?
Different regex engines (PCRE, Java, Python, Go's RE2) support slightly different syntax. The most common gotchas: lookbehinds (not in RE2), named groups syntax, and how backslashes need to be escaped inside string literals. The code snippets above already escape correctly for each language.
Can I edit this pattern and test it live?
Yes — use the live tester above. Type your test string and toggle flags (g, i, m, s, u, y) to see matches highlighted instantly, including capture groups.

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