What Do Credit Card Numbers Mean?
March 10, 2008
Have you ever wondered what sort of information in encoded in your credit card number? Well, wonder no more, I have the answer…
The first digit is the system number, and it’s always a 3, 4, 5, or 6. Here’s how it works:
3 = Travel or entertainment cards such as Amex or Diner’s Club
4 = Visa
5 = MasterCard
6 = Discover
For Visa, the numbers are either 13 or 16 digits long. Digits 2-6 are the bank number, digits 7-12 or 7-15 are the account numbers, and the 13th or 16th numbers serve as the ‘check digit’ which is essentially a checksum that tells if the number as a whole is legitimate.
For MasterCard, the number is always 16 digits long and the second digit is either a 1, 2, 3, 4, or 5. Digits 2 and 3, 2-4 2-5, or 2-6 are the bank number. The digits after the bank numbers up through the 15th digit are the account number. The 16th digit is a check digit.
For American Express, the card number always starts with 34 or 37 (Diner’s Club starts with 36 or 38). The 3rd and 4th digits indicate type (business vs. personal) and currency. Digits 5-11 are the account number, digits 12-14 are the card number with the accounts, and digit 15 is the check digit.
[Sources: How Stuff Works, Credit Cards Explained]
Posted in Credit Card Facts
March 18th, 2008 at 8:42 am
I used to work in credit card processing and I used to know what bank each 6 digit credit card prefix went to. It was a great party trick…
March 25th, 2008 at 5:47 pm
I was told about a scheme from a fraud prosecutor in a Texas county a few months ago….he said a fast food worker memorized the prefixes for all the major cards, and noticed that receipts print the last four digits. So when she’d swipe a card, she’d memorize the few numbers in the middle, then already had the rest of the number between the standard prefix and the last four digits on the receipt. She was using those numbers to buy things online, but was finally caught for the scam. While it’s interesting to know what the numbers mean, it’s worrisome that people can abuse this information.