What Is A Credit Card Number? The Meaning of Each Digit (2024)

A credit card number is usually 15-16 digits long, but it could be as many as 19 digits or as few as 13 in some cases. Each of these individual credit card numbers has meaning. And understanding the significance of each makes it easier to spot fraud, in addition to giving you an inside look at how credit cards work.

To get you started, we’ll give you a quick overview of the four major parts of a credit card number, before analyzing each in more detail.

Credit Card Numbers Meaning

• 1^st Number: Known as the Major Industry identifier (MII), the first digit of a credit card number tells you what type of company a card is affiliated with. This could be an airline, a banking institution or a retailer, for example. It also helps indicate which major card network the card belongs to: American Express(3), Visa (4), Mastercard (5) or Discover (6).
• Numbers 2-6: Together with the first digit, these numbers represent the Issuer Identification Number (IIN), also called the Bank Identification Number (BIN). This clarifies which credit card company a card comes from, which isn’t always obvious.
• Numbers 7-18*: The seventh and all subsequent digits in a card number, save for the last, identify the individual account in question. You will only see a few of these digits printed on your monthly statement. There are 1 trillion possible account numbers for each credit card issuer, according to Discover.
• Final Number: The last digit serves as a final check for payment processors. It’s basically part of a math trick to verify that a card number is genuine.

Now that you’ve got your bearings, let’s get into a bit more detail.

The First Number

The first digit of your credit card number is known as the Major Industry Identifier (MII). It indicates whether your card is affiliated with an airline, another type of travel provider or certain other special interests. It can also give you a sense of how the funds might be used and what network the card belongs to.

With the exception of store-specific credit cards, which don’t conform to the same rules, most consumers will only ever encounter cards that begin with 3, 4, 5 and 6. These numbers generally correspond with the four major card networks: Visa, Mastercard, American Express and Discover. But as you can see below, American Express and Discover are unique from their more-widely-accepted counterparts. In particular, it takes multiple digits to identify their cards.

This first digit and the five that follow it make up a card’s Issuer Identification Number. You can learn more about that in the next section.

Issuer Identification Numbers: The First 6 Digits

A card’s Issuer Identification Number (IIN), or Bank Identification Number (BIN), indicates which credit card company it originates from and clarifies which card network it belongs to. And that, in turn, tells you a bit about the benefits available to cardholders.

Below, you can find examples for each of the 10 largest U.S. credit card issuers. Just remember that a single large issuer can have numerous IINs, if it offers a broad portfolio of credit cards.

Digits 7-18: Account Numbers

This is your individual account number. It can have as many as 12-digits, the last three of which will be included on your monthly statements, along with the final digit of the card number. Although your account number will change when you get a replacement credit card because the original was lost or stolen, you won’t actually be opening a new account. So this won’t affect your credit score.

The Final Digit: The Validator

The last number helps protect the account from unauthorized use by catching common transcription errors made by either humans or machines when inputting series of numbers. How and why this works are matters too complex to cover in the course of this discussion, but feel free to read up on the topics if you wish!

Card Number Tips & Tricks

Understanding the meaning of your credit and debit cards’ numbers is far from useless knowledge. Not only does it give you a peek into the inner workings of the payments market, but it can also help protect you from fraud.

1. Divide By 10: All legitimate credit card numbers are divisible by 10, but not obviously so. You can’t simply divide your full 13-to-19 digit card number by 10 and expect this trick to work. You have to know the code. Here’s how it goes for a 16-digit card:
   1. Double every other number (starting with the first)
   2. Separate any double-digit numbers that result into the sum of their parts (e.g. 14 becomes 1 and 4)
   3. Calculate the sum of the resulting numbers
   4. Calculate the sum of the numbers that were not doubled (i.e. the odd digits in the card number)
   5. Add the result of step c to the result of step d
   6. Divide by 10

   If the result ends in 0, then the card number is real. If not, it’s time to call customer service to report a case of fraud. By the way, you can do the same thing with a 15-digit card number. Just start by doubling the second number rather than the first.

2. Avoid Writing Down Your Full Account Number: There’s a reason that credit card companies don’t include your full account number on account communications. The fewer times the full thing is ever recorded intact, the safer it is. And only a handful of digits are needed to identify an account as your own. So avoid storing your full card number, whether on paper or digitally on a computer or mobile device.
3. Always Report Lost & Stolen Cards: This is an obvious one, but it’s always important to limit the potential damage when your card could be in someone else’s hands. Credit card companies make it very easy to report cards missing, either online or over the phone. And it usually doesn’t take too long to get a replacement. You can check out WalletHub’s guide on lost and stolen credit cards for more info.

If you’d like to learn more about how credit cards work, we recommend reading WalletHub’s New to Credit Guide and article on how credit card transactions are processed. Finally, if your interest in the meaning of credit card numbers stems from a desire to get a new card, you can’t go wrong with one of WalletHub’s editors’ picks for the year’s best credit cards. You can also try our free CardAdvisor tool for more-tailored suggestions.

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