How to Identify a Credit Card by the Account Number

Every credit card issued on the planet has its own unique account number. Credit card companies use these sets of digits to personalize accounts for owners, but there are ways to distinguish different issuers and types of cards. The writers at Ecommerce Platforms explain that credit card account numbers are shown on fronts and backs of cards, and you only need a bit of information to figure out who the issuer is.

There are countless credit card companies out there, and CardRates.com lists the largest ones. Two of the most familiar are Visa and Mastercard, which are both payment network processors. They offer their own cards like Visa Platinum and World Mastercard and also partner with banks to offer cards like the Wells Fargo Active Cash card.

Banking institutions like Citibank and Capital One also issue credit cards and partner with Visa and Mastercard. Some of the other largest credit card issuers include Bank of America, American Express, Discover, Synchrony Financial, Barclays U.S., CreditOne Bank and U.S. Bank. And besides these leaders, there are industry credit cards from travel and entertainment companies like Diners Club and American Express. You can also get credit cards from retail stores and airlines.

Credit card numbers are not created randomly – they all start with a specific number that corresponds to their industry. Airline credit cards start with a 1 or a 2, and Diners Club and American Express cards begin with a 3. Every Visa card starts with a 4, Mastercard starts with a 5 and Discover credit cards start with a 6. The following six numbers identify which bank has issued the card, and this is followed by the cardholder's personal account number. The very last number, or "checksum," uses the preceding numbers to verify that the card is valid.

All major credit cards use the first six digits as Issuer Identification Numbers (IIN). The 6011 credit card type includes Discover Cards, which start with 6011, 6221, 644 and 65. In addition, American Express Cards can start with 34 or 37, Mastercard with 51 through 55 and Visa with 4.

Checksum formulas validate identification numbers, including credit card account numbers. Credit card issuers use the Luhn algorithm checksum formula to validate the identification numbers. This algorithm is also used for Canadian Social Insurance numbers. It is used to protect against accidental errors, not as a form of security.

dCode.fr has an online tool that can check Luhn numbers for you. All you have to do is enter the credit card number you want to check, click "verify" and look on the left side of the page. It can also generate valid numbers and perform other mathematical calculations. Proceed with caution with online tools like this, however. It's never wise to enter credit card numbers in their entirety if the site is not trustworthy. Even if it is, the site could fall prey to hackers, jeopardizing your information.

Although credit cards and debit cards both have 16-digit card numbers, magnetic stripes, chips and expiration dates, credit cards allow users to make purchases and pay later. Debit and ATM cards automatically remove money from existing bank accounts, typically checking accounts. Debit card-issuing organizations can be identified by their account numbers in much the same ways as credit cards are.

Those identifying numbers can be different in other parts of the world, though. For India, the first number is the Major Industry Identifier, or MII. Number 1 is for an independent sales organization or other industry; 2 and 3 are for airlines and other industries; 4 is for American Express or Food Club; 5 is for Visa and 6 is for Mastercard. The following nine numbers link to bank account numbers, and that last number, called a Check Digit, works like a checksum.