About This Tool
Convert any US phone number into five standard formats with this free formatter. Paste a phone number in any format and instantly see it displayed as National (xxx) xxx-xxxx, Dashed xxx-xxx-xxxx, International +1 xxx xxx xxxx, E.164 +1xxxxxxxxxx, and Dotted xxx.xxx.xxxx. The tool strips all non-digit characters, auto-detects whether the input includes a country code, and validates the area code and exchange against US numbering rules. Each formatted output includes a copy button so you can grab the exact format you need and paste it into spreadsheets, contact forms, CRM systems, or databases. Useful for cleaning up imported contact lists, standardizing phone fields in CSV files, or preparing data for APIs that require specific phone formats like E.164. No signup and nothing is stored.
Understanding US Phone Number Formats
US phone numbers consist of a 3-digit area code, a 3-digit exchange (central office code), and a 4-digit subscriber number. The full number is 10 digits, and the international dialing code for the United States is +1. Different formats arrange these same 10 digits in various ways for readability or technical requirements.
- National: (555) 123-4567 - The most common US format with parentheses around the area code. Used in print, signage, and casual communication.
- Dashed: 555-123-4567 - Common in forms and databases. Easy to type on keyboards.
- International: +1 555 123 4567 - The ITU-T E.123 international format with country code and spaces.
- E.164: +15551234567 - The standardized international format used by telecom APIs, Twilio, and SMS gateways. No spaces or punctuation.
- Dotted: 555.123.4567 - Used in some corporate environments and technical documentation.
What Is E.164 Format?
E.164 is the international public telecommunication numbering plan defined by the International Telecommunication Union (ITU). It specifies that a phone number should be written as a plus sign followed by the country code and subscriber number with no spaces, dashes, or parentheses. The maximum length is 15 digits.
For US numbers, E.164 format is +1 followed by the 10-digit number: +15551234567. This format is required by most telephony APIs, cloud communication platforms, and international messaging services. When building applications that send SMS, make voice calls, or store phone numbers in a database, E.164 is the recommended canonical format because it eliminates ambiguity about the country of origin.
US Numbering Plan Rules
The North American Numbering Plan (NANP) governs phone number allocation in the US, Canada, and several Caribbean nations. Under NANP rules, area codes and exchange codes follow specific constraints:
- Area codes cannot start with 0 or 1
- Exchange codes (the middle 3 digits) cannot start with 0 or 1
- Area codes in the format N11 (like 211, 311, 411) are reserved for special services
- The area code 800 and similar codes (888, 877, 866, 855, 844, 833) are toll-free
This tool flags numbers where the area code or exchange starts with 0 or 1, as these do not conform to standard NANP rules. The formatting still works, but the warning lets you know the number may not be a valid US telephone number.
Cleaning Phone Data in Bulk
When importing contact lists from spreadsheets or CSV files, phone numbers often arrive in inconsistent formats. Some entries use parentheses, others use dashes, some include the country code, and some have extra characters like spaces or dots. This inconsistency causes problems for CRM systems, dialing software, and database queries.
Use this tool to determine the correct format for your system, then apply the same logic across your dataset. For E.164 formatting at scale, the rule is simple: strip all non-digits, ensure the result is 10 or 11 digits (removing a leading 1 if 11 digits), then prepend +1. For display in customer-facing contexts, the National format with parentheses is the most familiar to US readers. For database storage, E.164 is the gold standard because it removes all ambiguity.
When to Use Each Format
Choosing the right format depends on the context:
- Print and marketing: National format (555) 123-4567 for maximum readability
- Web forms and databases: Dashed format 555-123-4567 or E.164 for storage
- International communication: International format +1 555 123 4567 for clarity across borders
- APIs and software: E.164 format +15551234567 for unambiguous machine processing
- Internal documentation: Dotted format 555.123.4567 used by some organizations
Consistency matters more than which specific format you choose. Pick one format for each use case in your organization and apply it everywhere. This tool helps you see all options at once so you can make an informed choice.