Phone Number Formatter & Formatting Tool

Complete Guide: How to Format Telephone Numbers & Standard Phone Number Format

Welcome to the developer-standard phone number formatter and telephone number formatting tool. In global CRM systems, checkout flows, SMS marketing platforms (Twilio, Vonage), and website design, phone numbers are submitted in countless inconsistent variations: with or without parentheses, dashes, dots, spaces, or international country codes. Knowing the correct telephone number format and how to format telephone numbers ensures high SMS deliverability, eliminates database duplicate records, and provides smooth click-to-call mobile user experiences.

The E.164 Proper Phone Number Format

The international telecommunications union standard proper phone number format is ITU-T E.164:

Key requirements of the E.164 standard telephone number format:

• Must start with a plus sign (+).
• No punctuation: zero dashes, brackets, parentheses, or dots.
• No leading trunk zeros (for example, the UK mobile number 07911 123456 becomes +447911123456).

Standard Phone Number Format Comparison

Phone Number Formatter JavaScript (How to Format in JS)

When building web applications, developers frequently look for a phone number formatter javascript or javascript to format phone number. Using our phone number formatter js snippet, you can attach live formatting on an HTML input's oninput event:

const input = document.getElementById('phone-field');
input.addEventListener('input', function(e) {
  let x = e.target.value.replace(/\D/g, '').match(/(\d{0,3})(\d{0,3})(\d{0,4})/);
  e.target.value = !x[2] ? x[1] : '(' + x[1] + ') ' + x[2] + (x[3] ? '-' + x[3] : '');
});
        

Frequently Asked Questions (FAQ)