UK Phone Number Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching uk phone number, ported and verified for JavaScript. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// UK Phone Number
// ReDoS-safe | RegexVault — Localization > Phone Numbers

const ukPhoneNumberRegex = /^(?:\+44|0)(?:\s|-)?(?:[1-9][0-9]{1,4})(?:\s|-)?(?:[0-9]{3,4})(?:\s|-)?(?:[0-9]{3,4})$/;

function validateUkPhoneNumber(input: string): boolean {
  return ukPhoneNumberRegex.test(input);
}

// Example
console.log(validateUkPhoneNumber("+44 20 7946 0958")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Phone Numbers category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. 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

UK uses a complex numbering plan. 020 = London, 0161 = Manchester, 07xxx = mobile, 0800 = freephone, 01xxx/02xxx = geographic. The (0) is sometimes shown in international format (+44 (0)20...) but not dialed.