All You Need to Know About Credit Card Numbers

By Kim Franke-Folstad · May 16, 2024 · 8 minute read

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All You Need to Know About Credit Card Numbers

A credit card number — that long string of digits on the front or back of every credit card — contains more information than you might think. Though credit card numbers may seem rambling and random, each digit actually has a specific purpose and place. The number you see on a credit card provides information about the individual account holder, the payment network, and the card issuer. It also uses a special formula to help prevent transaction errors and fraud.

Here, gain a deeper understanding of the significance of each digit.

What Is a Credit Card Number?

A credit card number is a set of digits — usually 16 — that’s printed on the front or back of a credit card.

It’s important to note that your credit card number is not the same thing as your account number. Your credit card number includes your account number, but it has additional digits (an account number typically has 12), and it provides more information. When you make a credit purchase online or on the phone, you can expect to be asked for your full card number to authenticate the transaction.

Though the information provided by every credit card number is basically the same, the format may differ a bit from card to card: Sometimes the numbers are raised; sometimes they’re flat. And generally, although not always, the digits are divided into four sets of four (xxxx xxxx xxxx xxxx).

The format for credit cards and debit cards is similar — which is why you might pull out the wrong card from time to time.

Who Decides What Your Credit Card Number Is?

Your credit account number is assigned by the financial institution that is your credit card issuer. But the structure and sequence of the digits in your credit card number must follow a rigid set of standards imposed by the International Organization of Standardization (ISO) and enforced by the American Network of Standards Institute (ANSI).

All card issuers follow these rules, so consumers can use their cards or card numbers no matter where they are in the world.

Credit Card Number Structure

Even if you know what a credit card is and how credit cards work, you may not be familiar with what the numbers on your card mean. Though most credit card numbers have 16 digits, the length may vary. Of the four major card networks, Visa, Mastercard, and Discover card numbers all have 16 digits, while American Express card numbers have only 15. Here’s what those digits actually mean.

The First Number: Industry Identifier

The first digit in a credit card number is known as the Major Industry Identifier (MII), and it can tell you both the industry associated with the card and the payment network.

Payment Network

Most credit cards start with a 3, 4, 5, or 6. These numbers represent the major payment networks, each of which has its own identifier:

•   American Express cards begin with a 3

•   Visa cards begin with a 4

•   Mastercard cards typically start with a 5, but may start with a 2

•   Discover cards start with a 6

Knowing your credit card’s payment network can be useful, because the network determines which merchants will accept the card. Your favorite local market or small boutique might accept credit card payments with a Mastercard, Visa, or Discover card, for example, but they may not let you pay with American Express.

Recommended: When Are Credit Card Payments Due

Industry Association

There are many different types of credit cards. Some credit cards are meant for general use, while others may be geared to a more specific purpose. The MII can tell you which type of industry your card is most associated with. Here’s what some MIIs generally mean:

•   1: Airlines

•   2: Airlines and financial

•   3: Travel and entertainment

•   4: Banking and financial

•   5: Banking and financial

•   6: Merchandising and banking

•   7: Petroleum

•   8: Health care and communications

•   9: Government and other

The Next 5 Numbers: Identification Numbers

The next five digits complete the Bank Identification Number (BIN), or Issuer Identification Number (IIN). This can tell you who the card issuer is.

The credit card issuer is the financial institution that offers the card and manages your account. Some of the largest credit card issuers in the U.S. include American Express, Bank of America, Capital One, Chase, Citi, Wells Fargo, and Discover.

When you apply for a credit card, it’s the issuer who accepts or declines your application. When you make a purchase, you’re borrowing money from the credit card issuer, and when you pay your bill, you’re paying back that money. Any time you check your balance, request a higher credit limit or a lower interest rate, or obtain a replacement card, you’re doing it through your credit card issuer.

Recommended: Does Applying For a Credit Card Hurt Your Credit Score

The Next 9-12 Numbers: Account Identifier

The remaining digits on the card — except for the very last one — identify the account and the cardholder.

Don’t worry, there isn’t a secret indicator in your card number that tells people how often you’re using your credit card or if you’re paying your bills on time. This part of your card number simply represents what account the card is connected to.

If your card is lost or stolen, or your card number is compromised in a credit card scam, you may notice that the number on your replacement card has changed, even if your account number hasn’t. So if you’re keeping a list of card numbers in a secure place, you may have to update that card number.

Recommended: Tips for Using a Credit Card Responsibly

The Last Number: Checksum

The last digit of a credit card number is referred to as the “checksum” or “check digit.” Card issuers and payment networks use it to catch errors and help protect against unauthorized card use. (Let’s face it: Even if you follow all the so-called credit card rules, things can happen.)

When a card is used for a purchase or payment, this digit is used as part of a mathematical formula called the Luhn algorithm to verify the card’s validity. If the checksum doesn’t work, the transaction is quickly rejected. (If you’ve ever mistyped your card number when shopping online, you’ve seen this algorithm in action.)

Most major networks use the final digit as the checksum. However, if you have a Visa credit card, it may be the 13th digit.

What About the Other Numbers on the Card?

Besides the card number, there are two other sets of digits that also can play a critical role when you use your credit card.

Card Verification Value (CVV)

The Card Verification Value (or CVV number on a credit card) or Card Verification Code (CVC) is also used to protect the card owner. If you do a lot of online shopping, you’re probably very familiar with this three- or four-digit number, which usually is found on the back of a credit card near or inside the signature strip.

On some cards, there may be seven digits in this spot. If this is the case, the first four digits you see are the last four digits of your credit card number. The last three digits in the grouping represent the CVV.

If you have an American Express card, the CVV is a four-digit number located on the front of the card, just above the logo.

The CVV is designed to help protect against identity theft. If you aren’t presenting your card in person during a transaction (because you’re using it online or over the phone), providing the CVV can help prove you’re in possession of the physical card.

Expiration Date

The expiration date offers yet another layer of protection for the card holder. Most businesses require that you provide the credit card number, the CVV, and the card’s expiration date when you make an online purchase.

The credit card expiration date typically appears on the front of the card with two digits for the month and two digits for the year (xx/xx). But if the account number is printed on the back of the card, you’ll likely find the expiration date there.

Even if you never need to use it to make a remote purchase or payment, it can be a good idea to glance at your card’s expiration date from time to time. That way, you can ensure you always have a current card in your wallet.

You’ll also know when it’s time to watch for the arrival of a replacement card. If a new card doesn’t arrive in the month the old card expires, you can call the issuer and immediately take steps to protect yourself if it appears the card has been lost or stolen. (The phone number for customer service is also on your card.)

The Takeaway

At first glance, the number on your credit card might look like a meaningless jumble. But if you take a closer look, you’ll find each digit has a purpose — to provide information, to help keep your account secure, and to make the card more user-friendly.

Whether you're looking to build credit, apply for a new credit card, or save money with the cards you have, it's important to understand the options that are best for you. Learn more about credit cards by exploring this credit card guide.


Where do I find my credit card number?

Your credit card number may appear on the front or back of your credit card.

Is the credit card number the same as the account number?

No, the two numbers are linked, but they are not the same. Your credit card number includes your account number, but it has more digits, and those extra digits are important to how each transaction is processed.

How long is a credit card number?

A credit card number typically has 16 digits, but the number can vary. American Express uses a 15-digit format for its credit cards.

Can a credit card number be stolen?

Yes. A credit card number can be stolen in multiple ways: through the theft of a physical card, during a data breach, with a card skimmer, or if the cardholder uses an unsecured website or public Wi-Fi when making a credit transaction.

Photo credit: iStock/max-kegfire

Financial Tips & Strategies: The tips provided on this website are of a general nature and do not take into account your specific objectives, financial situation, and needs. You should always consider their appropriateness given your own circumstances.

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