🔍Regex Recipes

Credit Card Format (Luhn Disclaimer)

Match credit card number formats. WARNING: Format match only - must run Luhn algorithm separately for validation.

Pattern

^\d{13,19}$

Explanation

Matches 13-19 digit numbers (covers most card types). Does NOT validate checksum - you must use Luhn algorithm separately.

Examples

Visa-length

Input

4532123456789012

Output

✓ Format match (16 digits)

Amex-length

Input

378282246310005

Output

✓ Format match (15 digits)

With spaces

Input

4532 1234 5678 9012

Output

✗ No match (contains spaces)

Code Examples

JavaScript

// Format validation only
const cardRegex = /^\d{13,19}$/;

// MUST also validate with Luhn algorithm
function luhnCheck(cardNumber) {
  const digits = cardNumber.split('').map(Number).reverse();
  const sum = digits.reduce((acc, digit, idx) => {
    if (idx % 2 === 1) {
      digit *= 2;
      if (digit > 9) digit -= 9;
    }
    return acc + digit;
  }, 0);
  return sum % 10 === 0;
}

function isValidCard(input) {
  const cleaned = input.replace(/\s/g, '');
  return cardRegex.test(cleaned) && luhnCheck(cleaned);
}

Try it Now

Open in Regex Tester

💡 Tips

Always implement Luhn checksum validation
Strip spaces/dashes before validation
Use PCI-compliant payment processors
Display only last 4 digits to users
Consider card type validation if needed

⚠️ Common Pitfalls

CRITICAL: Regex does NOT validate card number - use Luhn algorithm
Does not identify card type (Visa, Mastercard, etc.)
Does not handle spaces or dashes in formatted numbers
Never log or store full card numbers