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Phone Number Formatter - Format Phone Numbers for US, UK, International

Phone Number Formatter

Format and validate phone numbers for different countries

Enter a phone number (digits only or with formatting)

About Phone Number Formatting

Phone number formatting is essential for creating user-friendly interfaces and ensuring data consistency across systems. Different countries have different phone number formats, lengths, and conventions. Proper phone number validation and formatting helps prevent errors, improves user experience, and ensures compatibility with telecommunications systems. The E.164 international standard defines the format for international phone numbers, allowing up to 15 digits.

E.164 International Standard

E.164 is the international telephone numbering plan that ensures each device has a globally unique number:

  • Format: + [Country Code] [Subscriber Number]
  • Maximum Length: 15 digits (including country code)
  • Example: +1 555 123 4567 (US), +44 20 7123 4567 (UK)
  • No Formatting: E.164 uses digits only, no spaces or punctuation

US Phone Number Format

United States phone numbers follow the North American Numbering Plan (NANP):

  • Format: (NXX) NXX-XXXX where N is 2-9 and X is 0-9
  • Length: 10 digits (or 11 with country code 1)
  • Area Code: First 3 digits identify geographic region
  • Exchange Code: Next 3 digits identify local exchange
  • Subscriber Number: Last 4 digits identify individual line
  • Examples: (555) 123-4567, +1 (555) 123-4567

UK Phone Number Format

United Kingdom phone numbers vary by type and region:

  • Length: 10 or 11 digits (including area code)
  • Country Code: +44
  • London: 020 XXXX XXXX (11 digits total)
  • Other Cities: 01XX XXX XXXX or 01XXX XXXXXX
  • Mobile: 07XXX XXXXXX
  • Examples: +44 20 7123 4567, +44 7123 456789

Common Phone Number Formats by Country

Country Code Length Example Format
United States +1 10 +1 (555) 123-4567
United Kingdom +44 10-11 +44 20 7123 4567
Canada +1 10 +1 (416) 555-0123
Australia +61 9 +61 2 1234 5678
Germany +49 10-11 +49 30 12345678
France +33 9 +33 1 23 45 67 89
Japan +81 10 +81 3 1234 5678
China +86 11 +86 10 1234 5678

When to Use Phone Formatting

  • User Registration: Format phone numbers for consistent storage
  • Contact Forms: Display formatted phone numbers for better readability
  • SMS Systems: Normalize phone numbers before sending messages
  • CRM Systems: Standardize phone numbers in customer databases
  • Call Centers: Format phone numbers for click-to-call functionality
  • Data Import: Normalize phone numbers from various sources

Special Phone Numbers

Different countries reserve certain ranges for special services:

Type US/Canada UK Purpose
Emergency 911 999, 112 Police, Fire, Ambulance
Toll-Free 800, 888, 877, 866 0800, 0808 Free for caller
Premium Rate 900 09XX Paid services
Directory 411 118XXX Information services

Mobile vs Landline Numbers

Some countries assign different prefixes to mobile and landline numbers:

  • UK Mobile: Start with 07
  • UK Landline: Start with 01 or 02
  • US/Canada: No distinction by number (same format for both)
  • France Mobile: Start with 06 or 07
  • Germany Mobile: Start with 15, 16, or 17

Phone Number Validation Libraries

For production applications, consider using specialized libraries:

  • libphonenumber: Google's comprehensive phone number library (Java, C++, JavaScript)
  • phonenumbers (Python): Python port of libphonenumber
  • Twilio Lookup API: Cloud-based phone number validation and lookup
  • numverify: REST API for phone number validation

Common Formatting Conventions

  • Parentheses: (555) 123-4567 - US style for area code
  • Hyphens: 555-123-4567 - Simple separator
  • Spaces: 555 123 4567 - European style
  • Dots: 555.123.4567 - Alternative US style
  • Plus sign: +1 555 123 4567 - International format

Test Phone Numbers

Many countries reserve specific ranges for testing:

Country Test Numbers
United States (555) 0100 - (555) 0199 (reserved for fiction)
United Kingdom +44 20 7946 0xxx (fictional use)
Germany +49 30 0000 0000 (example numbers)

Best Practices

  • Store phone numbers in E.164 format (international standard)
  • Display phone numbers in local format for user's country
  • Always include country code for international compatibility
  • Remove all formatting before validation or storage
  • Accept multiple input formats but normalize to one storage format
  • Provide clear input instructions and examples
  • Use specialized libraries for complex validation needs
  • Consider click-to-call links on mobile devices

Privacy and Security

Important Notes:
  • Phone numbers are personal data - handle according to privacy laws
  • Implement consent mechanisms for SMS/call communications
  • Provide easy opt-out options for phone-based communications
  • Don't display full phone numbers publicly without consent
  • Use rate limiting to prevent abuse of phone validation
  • Consider two-factor authentication using phone numbers

Additional Resources