International Phone Number Validation Regex (E.164 Format)

Validate international phone numbers in E.164 format: starts with +, followed by country code and subscriber number (1-15 digits total).

Pattern Breakdown

^\+[1-9]\d{1,14}$

Components

Character Classes

• \+ - Literal plus sign (escaped, since + is a quantifier)
• [1-9] - First digit must be 1-9 (country codes don't start with 0)
• \d - Any digit (0-9)
• {1,14} - Quantifier: between 1 and 14 occurrences (total length 1-15 digits after +)

Examples

Valid:

• +15551234567 (US)
• +442071234567 (UK)
• +33123456789 (France)
• +8613800138000 (China)
• +123456789012345 (15 digits - maximum length)
• +12 (minimum: country code + 1 digit)

Invalid:

• 15551234567 (missing + sign)
• +05551234567 (country code can't start with 0)
• +1555123456789012345 (too long, 16 digits after +)
• + (no digits)
• +1-555-123-4567 (contains formatting characters)
• +1 555 123 4567 (contains spaces)

Implementation

JavaScript

const phoneRegex = /^\+[1-9]\d{1,14}$/;
phoneRegex.test('+15551234567'); // true
phoneRegex.test('+442071234567'); // true
phoneRegex.test('15551234567'); // false (missing +)
phoneRegex.test('+05551234567'); // false (starts with 0)

Python

import re
phone_regex = r'^\+[1-9]\d{1,14}$'
bool(re.match(phone_regex, '+15551234567'))  # True
bool(re.match(phone_regex, '+442071234567'))  # True
bool(re.match(phone_regex, '15551234567'))  # False (missing +)

Go

phoneRegex := regexp.MustCompile(`^\+[1-9]\d{1,14}$`)
phoneRegex.MatchString("+15551234567") // true
phoneRegex.MatchString("+442071234567") // true
phoneRegex.MatchString("15551234567") // false (missing +)

Limitations

1. No formatting: E.164 format doesn't allow spaces, dashes, or parentheses
2. No country code validation: Doesn't verify if country code is valid
3. No subscriber number validation: Doesn't check if number is valid for that country
4. Length only: Only validates format, not actual number validity
5. No extension support: E.164 doesn't include extensions

When to Use

• International phone number input
• SMS/MMS systems that require E.164 format
• VoIP applications
• Global applications supporting multiple countries
• When you need standardized phone number format

For production, consider:

• Using a library like libphonenumber for full validation
• Validating country codes against known list
• Formatting display version for users while storing E.164
• Handling country-specific number length requirements