Spanish Código Postal Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching spanish código postal, ported and verified for PHP. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Spanish Código Postal
// ReDoS-safe | RegexVault — Localization > Postal Codes

define('SPANISH_CDIGO_POSTAL_PATTERN', '/^(0[1-9]|[1-4][0-9]|5[0-2])[0-9]{3}$/');

function validate_spanish_cdigo_postal(string $input): bool {
    return (bool) preg_match(SPANISH_CDIGO_POSTAL_PATTERN, $input);
}

// Example
var_dump(validate_spanish_cdigo_postal("28001")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Spanish province codes 01-52. Madrid is 28, Barcelona is 08. Ceuta is 51, Melilla is 52. The Canary Islands (Gran Canaria 35, Tenerife 38) are Spanish territory.