Card Number Generator

How It Works

Card Number Structure

• Visa: Starts with 4, followed by 15 digits (16 digits total)
• Mastercard: Starts with 51-55, followed by 14 digits (16 digits total)
• American Express: Starts with 34 or 37, followed by 13 digits (15 digits total)
• JCB: Starts with 35, followed by 14 digits (16 digits total)

The Luhn Algorithm

All generated numbers are validated using the Luhn Algorithm, also known as the “modulus 10” algorithm. This is how it works:

1. Starting from the rightmost digit (excluding the check digit), double every second digit
2. If doubling results in a two-digit number, add those digits together
3. Add all digits together (both doubled and undoubled)
4. The check digit (last digit) is the number needed to make the total sum divisible by 10

This algorithm is used by major credit card companies to distinguish valid numbers from random number sequences.