Credit Card Number Generator & Validator

How to validate a credit card number

Every payment card number ends with a check digit computed with the Luhn algorithm (also called "modulus 10" or "mod 10", described in ISO/IEC 7812-1). It was designed to catch accidental typing errors before a transaction is even attempted. It is not a security feature: a number that passes the check is well formed, it is not necessarily attached to a real account.

The algorithm, step by step

1. Drop the last digit of the number: this is the check digit you want to verify.
2. Reverse the remaining digits.
3. Multiply the digits in odd positions (1st, 3rd, 5th...) by 2.
4. If a product is greater than 9, subtract 9 from it.
5. Add all the resulting digits together.
6. The check digit is (10 - sum mod 10) mod 10. If it equals the digit you dropped in step 1, the number is valid.

Anatomy of a card number

• MII: the first digit identifies the industry of the issuer.
• IIN / BIN: the first 6-8 digits identify the issuing institution.
• Account number: the digits between the IIN and the check digit.
• Check digit: the last digit, computed with the Luhn algorithm.

List of credit card formats