ISBN Validation Regular Expression

An ISBN (International Standard Book Number) is a unique identifier for books. There are two formats: ISBN-10 (10 digits, with the last digit potentially being X) and ISBN-13 (13 digits starting with 978 or 979). These regular expressions validate the format of ISBN numbers without hyphens or spaces. ISBNs are a specialized type of number pattern.

ISBN-10 Validation

ISBN-10 consists of 10 digits where the last digit can be X (representing 10). This format was used before 2007 and is still found on older books.

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

Explanation

^ - Start of the string.
(?:...) - Non-capturing group containing two alternatives.
\d{9}X - Nine digits followed by the letter X (uppercase).
| - Or operator separating the two alternatives.
\d{10} - Exactly 10 digits.
$ - End of the string.

Implementation

const isbn10Regex = /^(?:\d{9}X|\d{10})$/;
const isValidISBN10 = (isbn) => isbn10Regex.test(isbn);

import re

def is_valid_isbn10(isbn):
  isbn10Regex = r"^(?:\d{9}X|\d{10})$"
  return re.match(isbn10Regex, isbn) is not None

use regex::Regex;

fn is_valid_isbn10(isbn: &str) -> bool {
  let isbn10Regex = Regex::new("^(?:\d{9}X|\d{10})$")
    .expect("Could not parse ISBN-10 validation regex");
  isbn10Regex.is_match(isbn)
}

package main

import (
  "regexp"
)

func isValidISBN10(isbn string) bool {
  isbn10Regex := "^(?:\d{9}X|\d{10})$"
  re := regexp.MustCompile(isbn10Regex)
  return re.MatchString(isbn)
}

import Foundation

func isValidISBN10(_ isbn: String) -> Bool {
  let isbn10Regex = "^(?:\d{9}X|\d{10})$"
  return NSPredicate(format: "SELF MATCHES %@", isbn10Regex).evaluate(with: isbn)
}

using System;
using System.Text.RegularExpressions;

class Application {
  static bool IsValidISBN10(string isbn) {
    string isbn10Regex = "^(?:\d{9}X|\d{10})$";
    return Regex.IsMatch(isbn, isbn10Regex);
  }
}

import java.util.regex.*;

public class Application {
  public static boolean isValidISBN10(String isbn) {
    String isbn10Regex = "^(?:\d{9}X|\d{10})$";
    Pattern pattern = Pattern.compile(isbn10Regex);
    Matcher matcher = pattern.matcher(isbn);
    return matcher.matches();
  }
}

<?php
function isValidISBN10($isbn) {
  $isbn10Regex = "^(?:\d{9}X|\d{10})$";
  return preg_match("/" . $isbn10Regex . "/", $isbn);
}
?>

Test Cases

ISBN-10	Valid
0306406152
0345391802
043942089X
156619909X
0471958697
12345
123456789
12345678901
123456789A
X123456789
12345X6789

abcdefghij

ISBN-13 Validation

ISBN-13 consists of 13 digits and always starts with either 978 or 979. This format has been the standard since 2007 and is used for all new book publications.

^97[89]\d{10}$

Explanation

^ - Start of the string.
97 - The ISBN-13 prefix always starts with 97.
[89] - The third digit must be either 8 or 9 (forming 978 or 979).
\d{10} - Exactly 10 more digits to complete the 13-digit ISBN.
$ - End of the string.

Implementation

const isbn13Regex = /^97[89]\d{10}$/;
const isValidISBN13 = (isbn) => isbn13Regex.test(isbn);

import re

def is_valid_isbn13(isbn):
  isbn13Regex = r"^97[89]\d{10}$"
  return re.match(isbn13Regex, isbn) is not None

use regex::Regex;

fn is_valid_isbn13(isbn: &str) -> bool {
  let isbn13Regex = Regex::new("^97[89]\d{10}$")
    .expect("Could not parse ISBN-13 validation regex");
  isbn13Regex.is_match(isbn)
}

package main

import (
  "regexp"
)

func isValidISBN13(isbn string) bool {
  isbn13Regex := "^97[89]\d{10}$"
  re := regexp.MustCompile(isbn13Regex)
  return re.MatchString(isbn)
}

import Foundation

func isValidISBN13(_ isbn: String) -> Bool {
  let isbn13Regex = "^97[89]\d{10}$"
  return NSPredicate(format: "SELF MATCHES %@", isbn13Regex).evaluate(with: isbn)
}

using System;
using System.Text.RegularExpressions;

class Application {
  static bool IsValidISBN13(string isbn) {
    string isbn13Regex = "^97[89]\d{10}$";
    return Regex.IsMatch(isbn, isbn13Regex);
  }
}

import java.util.regex.*;

public class Application {
  public static boolean isValidISBN13(String isbn) {
    String isbn13Regex = "^97[89]\d{10}$";
    Pattern pattern = Pattern.compile(isbn13Regex);
    Matcher matcher = pattern.matcher(isbn);
    return matcher.matches();
  }
}

<?php
function isValidISBN13($isbn) {
  $isbn13Regex = "^97[89]\d{10}$";
  return preg_match("/" . $isbn13Regex . "/", $isbn);
}
?>

Test Cases

ISBN-13	Valid
9780306406157
9780345391803
9780439420891
9781566199094
9780471958697
978030640615
97803064061578
9770306406157
9880306406157
123456789012
978-0-306-40615-7

abcdefghijklm

Note

These regular expressions only validate the format of ISBN numbers. For complete validation, you should also verify the check digit using the appropriate algorithm. ISBN-10 uses modulo 11, while ISBN-13 uses modulo 10. Additionally, ISBNs are often formatted with hyphens (e.g., 978-0-306-40615-7), but these patterns match only the raw numeric format without separators.