What is the best regex pattern for phone numbers?

The best pattern depends on your needs. For US phone numbers: (\\+\\d{1,3}[- ]?)?\$?\\d{3}\$?[- ]?\\d{3}[- ]?\\d{4} matches formats like (555) 123-4567, +1-555-123-4567, and 5551234567. For international numbers, a more flexible pattern is needed.

How do I validate international phone numbers?

International phone numbers vary widely in format. A flexible pattern like \+?\d{1,4}[-.\s]?$?\d{1,3}$?[-.\s]?\d{1,4}[-.\s]?\d{1,9} can match many international formats. For strict validation, use a library like Google's libphonenumber.

Should phone regex match formatting characters?

It depends on your use case. If users enter phone numbers with formatting (parentheses, dashes, spaces), your regex should accept those characters. Consider normalizing the input by stripping non-digit characters before validation for more reliable matching.

Can regex validate phone number extensions?

Yes. Add an optional extension group to your pattern: (ext|x|extension)\s?\d{1,5}. Combine it with the base phone pattern to match numbers like (555) 123-4567 ext 123.

What's the difference between US and international phone regex?

US phone regex is specific: it expects 10 digits, often with area code in parentheses and a dash separator. International regex must be more flexible to accommodate varying country codes, digit counts, and formatting conventions across different countries.

How do I handle phone numbers with country codes?

Make the country code optional with a group: (\+\d{1,3}[- ]?)?. This matches +1, +44, +86, etc. followed by an optional separator. The rest of the pattern handles the local number format.

Phone Number Regex — Match and Validate Phone Numbers

How Phone Number Regex Works

Phone number regex patterns need to handle multiple formatting conventions while still catching invalid input. The pattern is built from several optional and required groups:

(\+\d{1,3}[- ]?)?

Country code (optional): Matches a + sign followed by 1-3 digits and an optional separator (dash or space). The entire group is optional with the ? quantifier.

$?\d{3}$?

Area code: Matches exactly 3 digits with optional parentheses. The $ and $ escape the special characters, and ? makes each optional.

[- ]?\d{3}[- ]?\d{4}

Phone number: Matches 3 digits, an optional separator, then 4 digits. This handles the standard XXX-XXXX format.

Phone Number Formats by Country

Phone number formats vary significantly around the world. Here are regex patterns for common international formats:

🇺🇸 United States

(\+1[- ]?)?$?\d{3}$?[- ]?\d{3}[- ]?\d{4}

10 digits with optional +1 country code. Formats: (555) 123-4567, +1-555-123-4567, 555.123.4567

🇬🇧 United Kingdom

(\+44[- ]?)?\d{4}[- ]?\d{6}

10 digits with optional +44 country code. Formats: +44 20 7946 0958, 020 7946 0958

🌐 International (Generic)

\+?\d{1,4}[-.\s]?$?\d{1,3}$?[-.\s]?\d{1,4}[-.\s]?\d{1,9}

Flexible pattern that matches many international formats. Good for general-purpose validation when you need to support multiple countries.

Common Phone Number Patterns

Here are the most commonly needed phone regex patterns, ready to copy and use:

US Phone (Flexible)

(\+\d{1,3}[- ]?)?$?\d{3}$?[- ]?\d{3}[- ]?\d{4}

Matches most US phone formats with optional country code

US Phone (Strict)

^$?\d{3}$?[-.\s]?\d{3}[-.\s]?\d{4}$

Exactly 10 digits, no country code, common separators

International (with +)

^\+\d{1,3}\d{4,14}$

Country code starting with + followed by 4-14 digits

Phone with Extension

(\+\d{1,3}[- ]?)?$?\d{3}$?[- ]?\d{3}[- ]?\d{4}(\s?(ext|x|ext.)\s?\d{1,5})?

US phone number with optional extension

Digits Only

^\d{10,15}$

Matches phone numbers that are 10-15 digits with no formatting

Phone Regex Edge Cases

Phone number validation has many edge cases. Here's what to watch out for:

Formatting variations

Users may enter (555) 123-4567, 555-123-4567, 555.123.4567, or 5551234567

Country codes

+1 for US, +44 for UK, +86 for China — make them optional for domestic apps

Extensions

Some numbers include ext 123 or x456 at the end

Toll-free numbers

800, 888, 877, 866, 855, 844, 833 are US toll-free prefixes

Short codes

SMS short codes (like 12345) are only 5 digits

International prefixes

00 is the international dialing prefix in many countries (instead of +)

Best Practices for Phone Number Validation

Normalize before validating
Strip all non-digit characters (except leading +) before applying regex. This handles different formatting conventions automatically.
Be flexible with input format
Accept multiple formats and normalize internally. Users should be able to enter phone numbers however they're comfortable.
Use regex for format, not existence
Regex can verify a number looks valid but cannot confirm it exists. For critical applications, use SMS or call verification.
Consider using a specialized library
For international phone validation, Google's libphonenumber provides more accurate results than regex alone.

Phone Regex in Code

Here's how to use phone number regex in popular programming languages:

JavaScript

const phoneRegex = /^(\+\d{1,3}[- ]?)?\(?\d{3}\)?[- ]?\d{3}[- ]?\d{4}$/;
const isValid = phoneRegex.test("(555) 123-4567"); // true

Python

import re
phone_regex = r'^(\+\d{1,3}[- ]?)?\(?\d{3}\)?[- ]?\d{3}[- ]?\d{4}$'
is_valid = re.match(phone_regex, "+1-555-123-4567")