What regex validates a US phone number?

Use /^\+?1?[-. ]?$?[0-9]{3}$?[-. ]?[0-9]{3}[-. ]?[0-9]{4}$/ to match common US formats like (555) 555-5555, 555-555-5555, +1 555 555 5555, and 5555555555.

How do I validate an international phone number with regex?

The E.164 international standard format is +[country code][subscriber number]. The regex /^\+[1-9]\d{1,14}$/ matches any valid E.164 number (8–15 digits after the +). For more flexible matching use /^\+?[1-9]\d{7,14}$/.

What regex matches Indian mobile numbers?

Indian mobile numbers are 10 digits starting with 6, 7, 8, or 9. Use /^[6-9]\d{9}$/ for bare 10-digit numbers, or /^(?:\+91|0)?[6-9]\d{9}$/ to optionally allow the +91 country code or leading 0.

Should I use regex or a library to validate phone numbers?

For strict international validation, Google's libphonenumber library (available in JavaScript as libphonenumber-js, in Python as phonenumbers) is far more reliable than regex alone. It understands country-specific rules, area codes, and number length. Use regex only for quick format checks or when you cannot add a dependency.

How do I strip non-digit characters before validating?

In JavaScript: const digits = phone.replace(/\D/g, ''); In Python: digits = re.sub(r'\D', '', phone). After stripping, check the digit count: 10 for US domestic, 11 with country code, 7–15 for international.

Why does my phone regex reject valid numbers?

Common issues: (1) you forgot to anchor with ^ and $ so the regex matches a substring, (2) the pattern doesn't handle optional country code (+1), (3) you're not allowing all formatting characters (spaces, dashes, parentheses, dots). Test edge cases like +1 (800) 555-0123 and 8005550123 using the Regex Tester above.

Regex for Phone Number Validation — Patterns for US, UK, India & More

Why Phone Number Regex is Harder Than Email Regex

Phone number formats are wildly inconsistent across countries, carriers, and user habits. A US number might appear as 5551234567, (555) 123-4567, 555-123-4567, +1-555-123-4567, or +1 (555) 123.4567. All of these represent the same number. Unlike email, where the @ symbol provides a reliable structural anchor, phone numbers have no universal marker — you are primarily counting digits.

This is why most senior developers recommend normalising the input first (stripping all non-digit characters) and then applying a digit-count check, rather than trying to write one mega-regex that handles every formatting variant.

Pattern Reference by Country

United States & Canada (NANP)

// Flexible — handles most common formats including optional country code
const US_PHONE = /^\+?1?[-. ]?\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;

// Strict E.164 US format
const US_E164  = /^\+1[2-9]\d{2}[2-9]\d{6}$/;
// Note: area codes starting with 1 or 0 are invalid in NANP

// After stripping non-digits and optional leading 1:
const US_DIGITS = /^[2-9]\d{9}$/;

India

// 10-digit mobile starting with 6–9 (Airtel, Jio, Vi, BSNL)
const IN_MOBILE = /^[6-9]\d{9}$/;

// With optional +91 or 0 prefix
const IN_FULL = /^(?:\+91|91|0)?[6-9]\d{9}$/;

// Matches: 9876543210, +919876543210, 09876543210
// Rejects:  1234567890 (starts with 1), 98765432 (too short)

United Kingdom

// UK mobile (07xxx)
const UK_MOBILE = /^(?:\+44|0)7\d{9}$/;

// UK landline (01xxx, 02xxx, 03xxx)
const UK_LANDLINE = /^(?:\+44|0)[123]\d{9}$/;

// Combined UK (landline + mobile)
const UK_ANY = /^(?:\+44|0)[0-9]\d{9}$/;

International E.164 (Recommended for global apps)

// Strict E.164: + followed by 8–15 digits
const E164 = /^\+[1-9]\d{7,14}$/;

// Permissive international (allows optional +, 7–15 digits)
const INTL = /^\+?[1-9]\d{6,14}$/;

// The E.164 standard (ITU-T Rec. E.164) defines a maximum of 15 digits
// including the country code. Country codes are 1–3 digits, so subscriber
// numbers can be 12–14 digits maximum.

Normalisation First — The Right Approach

Rather than a single complex regex, a two-step approach is more maintainable:

function normalizeAndValidate(phone, countryCode = 'US') {
  // Step 1: strip everything except digits and leading +
  const stripped = phone.replace(/[^\d+]/g, '');

  // Step 2: apply country-specific digit-count rules
  if (countryCode === 'US') {
    const digits = stripped.replace(/^\+1/, '').replace(/^1/, '');
    return /^[2-9]\d{9}$/.test(digits);
  }
  if (countryCode === 'IN') {
    const digits = stripped.replace(/^(?:\+91|91)/, '');
    return /^[6-9]\d{9}$/.test(digits);
  }
  // Fallback: E.164 check
  return /^\+[1-9]\d{7,14}$/.test(stripped);
}

Testing Your Phone Regex

Open the Regex Tester and run these test cases for the US flexible pattern:

✅ 5551234567
✅ (555) 123-4567
✅ +1-555-123-4567
✅ 555.123.4567
❌ 555-CALL-NOW (letters — adjust if you want to allow word substitution)
❌ 12345 (too short)
❌ +44 7700 900123 (UK — should fail US pattern)

Related Tools

Why Phone Number Regex is Harder Than Email Regex

Pattern Reference by Country

United States & Canada (NANP)

// Flexible — handles most common formats including optional country code
const US_PHONE = /^\+?1?[-. ]?\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;

// Strict E.164 US format
const US_E164  = /^\+1[2-9]\d{2}[2-9]\d{6}$/;
// Note: area codes starting with 1 or 0 are invalid in NANP

// After stripping non-digits and optional leading 1:
const US_DIGITS = /^[2-9]\d{9}$/;

India

// 10-digit mobile starting with 6–9 (Airtel, Jio, Vi, BSNL)
const IN_MOBILE = /^[6-9]\d{9}$/;

// With optional +91 or 0 prefix
const IN_FULL = /^(?:\+91|91|0)?[6-9]\d{9}$/;

// Matches: 9876543210, +919876543210, 09876543210
// Rejects:  1234567890 (starts with 1), 98765432 (too short)

United Kingdom

// UK mobile (07xxx)
const UK_MOBILE = /^(?:\+44|0)7\d{9}$/;

// UK landline (01xxx, 02xxx, 03xxx)
const UK_LANDLINE = /^(?:\+44|0)[123]\d{9}$/;

// Combined UK (landline + mobile)
const UK_ANY = /^(?:\+44|0)[0-9]\d{9}$/;

International E.164 (Recommended for global apps)

// Strict E.164: + followed by 8–15 digits
const E164 = /^\+[1-9]\d{7,14}$/;

// Permissive international (allows optional +, 7–15 digits)
const INTL = /^\+?[1-9]\d{6,14}$/;

// The E.164 standard (ITU-T Rec. E.164) defines a maximum of 15 digits
// including the country code. Country codes are 1–3 digits, so subscriber
// numbers can be 12–14 digits maximum.

Normalisation First — The Right Approach

Rather than a single complex regex, a two-step approach is more maintainable:

function normalizeAndValidate(phone, countryCode = 'US') {
  // Step 1: strip everything except digits and leading +
  const stripped = phone.replace(/[^\d+]/g, '');

  // Step 2: apply country-specific digit-count rules
  if (countryCode === 'US') {
    const digits = stripped.replace(/^\+1/, '').replace(/^1/, '');
    return /^[2-9]\d{9}$/.test(digits);
  }
  if (countryCode === 'IN') {
    const digits = stripped.replace(/^(?:\+91|91)/, '');
    return /^[6-9]\d{9}$/.test(digits);
  }
  // Fallback: E.164 check
  return /^\+[1-9]\d{7,14}$/.test(stripped);
}

Testing Your Phone Regex

Open the Regex Tester and run these test cases for the US flexible pattern:

✅ 5551234567
✅ (555) 123-4567
✅ +1-555-123-4567
✅ 555.123.4567
❌ 555-CALL-NOW (letters — adjust if you want to allow word substitution)
❌ 12345 (too short)
❌ +44 7700 900123 (UK — should fail US pattern)

Share your thoughts

Regex for Phone Number Validation

Why Phone Number Regex is Harder Than Email Regex

Pattern Reference by Country

United States & Canada (NANP)

India

United Kingdom

International E.164 (Recommended for global apps)

Normalisation First — The Right Approach

Testing Your Phone Regex

Related Tools

Frequently Asked Questions

Regex for Phone Number Validation

Why Phone Number Regex is Harder Than Email Regex

Pattern Reference by Country

United States & Canada (NANP)

India

United Kingdom

International E.164 (Recommended for global apps)

Normalisation First — The Right Approach

Testing Your Phone Regex

Related Tools

Frequently Asked Questions