ZIP Code Validation Regular Expression

A valid U.S. ZIP Code follows the format defined by the United States Postal Service (USPS). It can be either a 5-digit ZIP code (e.g., 12345) or a ZIP+4 code with an optional 4-digit extension (e.g., 12345-6789). This regex validates both formats according to USPS Publication 28. ZIP codes are a specialized type of number pattern.

Recommended Solution

^\d{5}(?:-\d{4})?$

Explanation

^ - Start of the string.
\d{5} - Exactly 5 digits for the basic ZIP code.
(?:-\d{4})? - Optional group for ZIP+4: a hyphen followed by exactly 4 digits.
$ - End of the string.

Notes

This regex validates the format of ZIP codes but does not verify if a ZIP code actually exists or is assigned to a location.
ZIP codes range from 00501 to 99950, but this regex accepts any 5-digit combination for simplicity.
The ZIP+4 extension provides more precise location information within a ZIP code area.
For international postal codes, different patterns are needed (e.g., Canadian postal codes use the format A1A 1A1).

Implementation

const zipCodeRegex = /^\d{5}(?:-\d{4})?$/;
const isValidZipCode = (zipCode) => zipCodeRegex.test(zipCode);

import re

def is_valid_zip_code(zip_code):
  zipCodeRegex = r"^\d{5}(?:-\d{4})?$"
  return re.match(zipCodeRegex, zip_code) is not None

use regex::Regex;

fn is_valid_zip_code(zip_code: &str) -> bool {
  let zipCodeRegex = Regex::new("^\d{5}(?:-\d{4})?$")
    .expect("Could not parse ZIP code validation regex");
  zipCodeRegex.is_match(zip_code)
}

package main

import (
  "fmt"
  "regexp"
)

func isValidZipCode(zipCode string) bool {
  zipCodeRegex := "^\d{5}(?:-\d{4})?$"
  re := regexp.MustCompile(zipCodeRegex)
  return re.MatchString(zipCode)
}

import Foundation

func isValidZipCode(_ zipCode: String) -> Bool {
  let zipCodeRegex = "^\d{5}(?:-\d{4})?$"
  return NSPredicate(format: "SELF MATCHES %@", zipCodeRegex).evaluate(with: zipCode)
}

using System;
using System.Text.RegularExpressions;

class Application {
  static bool IsValidZipCode(string zipCode) {
    string zipCodeRegex = "^\d{5}(?:-\d{4})?$";
    return Regex.IsMatch(zipCode, zipCodeRegex);
  }
}

import java.util.regex.*;

public class Application {
  public static boolean isValidZipCode(String zipCode) {
    String zipCodeRegex = "^\d{5}(?:-\d{4})?$";
    Pattern pattern = Pattern.compile(zipCodeRegex);
    Matcher matcher = pattern.matcher(zipCode);
    return matcher.matches();
  }
}

<?php
function isValidZipCode($zipCode) {
  $zipCodeRegex = "^\d{5}(?:-\d{4})?$";
  return (bool) preg_match("/" . $zipCodeRegex . "/", $zipCode);
}
?>

Test Cases

ZIP Code	Valid
12345
12345-6789
90210
00501
99950-0001
1234
123456
12345-
12345-678
12345-67890
abcde
12 345
12-345
(empty string)
-1234
12345-abcd