Phone Number Validator
Validate a phone number’s format for the US, UK, India, or international E.164 notation.
How this tool works
Select a country
US, UK, India, or international E.164 format.
Enter the number
With or without spaces, dashes, or a country code - it’s normalized automatically.
The right rule is applied
Length and prefix rules specific to that country’s numbering plan are checked.
See the formatted result
A valid number is shown nicely formatted, like (555) 123-4567 for US numbers.
Quick facts
- Category
- Validators
- Best for
- Validating a phone number field in a signup form
About this tool
Select a country - United States, United Kingdom, India, or generic international E.164 format - to check a phone number against that country’s specific length and prefix rules, since "valid" means something different depending on the numbering plan: a US number needs exactly 10 digits with an area code that can’t start with 0 or 1, a UK number needs 11 digits starting with 0 (or the +44 equivalent), and an Indian mobile number needs exactly 10 digits starting with 6 through 9. The E.164 option checks the international standard format used by telecom systems worldwide (a "+" followed by up to 15 digits with no leading zero). Whichever rule fails is named specifically in the error message, and a nicely formatted version of the number - like (555) 123-4567 for US numbers - is shown when validation passes. Runs entirely client-side.
Why use this tool
Country-specific rules
Applies the actual numbering plan for the selected country instead of one generic pattern.
Shows the formatted number
A valid number is displayed nicely formatted, not just marked as passing.
Four formats covered
US, UK, India, and international E.164 handle the most common validation needs in one tool.
Specific failure reasons
Names exactly which rule failed - wrong length, wrong prefix - not a generic invalid message.
Frequently asked questions
Every country defines its own numbering plan - the total digit count, which digits can start an area code or mobile prefix, and whether a leading 0 is part of the national format - so a single generic rule would either reject valid numbers or accept invalid ones for most countries. Selecting the country lets the tool apply the specific rule that number actually needs to satisfy, which is also exactly what a real phone system checks before allowing a call to connect.
No - this only confirms the number has the correct length and prefix pattern for its country’s numbering plan. Whether a specific number is actually assigned to someone, currently in service, or reachable can only be confirmed by the telecom carrier that owns that number range, which is outside what a browser-based format checker can determine.
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