How Many Numbers Are on a Credit Card?
Quick Answer
- Most credit cards have either 15 or 16 numbers, depending on the payment network.
- The digits identify your card's network, issuer and unique account.
- A final check digit helps catch errors when you enter your card number.

The numbers on your card may look random, but each digit serves a purpose. They help identify your card and ensure payments are processed correctly.
Most credit cards have either 15 or 16 numbers, and each represents specific identifying information necessary to complete a transaction. Here's what those numbers mean and how they work.
What Do All the Numbers on Your Credit Card Mean?
Credit cards in the Visa, Mastercard and Discover payment networks feature 16 digits, while those in the American Express network have just 15. No matter which network your card uses, the number is divided into four parts, and each one provides different information about your card.
First Digit: Card's Payment Network
The first number on your credit card identifies the payment network and the type of company that issued the card. Cards that start with a 4 are on the Visa network, while cards that start with a 6 are on Discover. Cards beginning with a 2 or 5 are Mastercard, and cards that start with a 3 are American Express or Diners Club. The first number can also reveal the kind of company that issued the card, such as a bank or travel company.
Digits 2 Through 6: Issuer Identification Number
The five digits after the network number tell you which card issuer you have and what card product it belongs to. As a group, the first six to eight digits are called the issuer identification number (IIN), or bank identification number (BIN). A bank may have several IINs if it offers a large number of credit cards since each card product is assigned its own code. New card issuers may receive an eight-digit IIN instead of a six-digit one.
Remaining Digits: Account Identifier
The numbers between the IIN and the final digit identify your account. This part of the card number is unique to you. Depending on the card network, it can run up to 12 digits long, which leaves issuers with more than a trillion possible account numbers to assign, according to Discover.
Final Digit: Check Digit
The last digit on your card is called the check digit. Its purpose is to validate the rest of the number. When you enter your card number, payment systems run it through the Luhn algorithm, which checks whether the number follows the correct pattern. Even if only one digit is entered wrong, the check will usually detect the error.
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