What Is a Primary Account Number?

A woman holds a phone and credit card.

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A primary account number is a unique number found on payment cards like debit and credit cards that identifies the card issuer and the cardholder account that is linked to that specific card.

Key Takeaways

  • The primary account number on a credit or debit card identifies the unique cardholder account and credit card issuer associated with the card.
  • The primary account number is made up of 16 to 19 digits, and you’ll recognize it as the long set of digits displayed on the front or back of a credit or debit card.
  • While primary account numbers are often referred to as “account numbers,” your primary account number is not the same number as your actual credit card account number.

Definition and Examples of Primary Account Number

A primary account number is a number on credit and debit cards that identifies the particular cardholder account and credit card issuer associated with the card. 

  • Alternate name: Account number

Chances are you’ve noticed your primary account number every time you’ve taken a look at your credit or debit card. 


The primary account number will be made up of 16 to 19 digits and is easy to identify because it’s displayed on either the front or back of a credit or debit card.

How Primary Account Numbers Work

While the long string of numbers on your credit card may look random at first glance, primary account numbers are not assigned randomly. A primary account number is created by following a system set by the American National Standards Institute (ANSI). The ANSI system codes the numbers to identify the card issuer, network, and account, with the goal of preventing fraud and identity theft. 

First Six Numbers

The first six numbers of a primary account number identify what credit card issuer or industry the card comes from. The first number in the sequence is known as the major industry identifier (MII). Here’s a breakdown of what the first number of a primary account number represents:

  1. Airlines
  2. Airlines and financial
  3. Travel and entertainment (includes American Express)
  4. Visa
  5. Mastercard
  6. Discover
  7. Petroleum
  8. Health care and communications
  9. Government

Next Five Numbers

The following five numbers refer to the bank identification number (BIN) or issuer identification number (IIN). These numbers indicate which credit card issuer provided the card and which network it belongs to.


Every credit card issuer has 1 trillion possible numerical configurations to assign account holders, with each issuer having different numbering systems. For example, how Visa assigns identifying numbers to account holders will vary from how Mastercard assigns its numbers.

Remaining Numbers

The remaining digits in a primary account number, excluding the very last number, identify the card’s individual account. This set of numbers can vary from nine to 12 digits. The final number is known as a “check sum” and represents whether or not a credit card number is valid. The check sum is generated by an algorithm that can detect errors when someone inaccurately transcribes a credit card number. 

Primary Account Number vs. Account Number

Even though primary account numbers are commonly referred to as “account numbers,” it’s important not to confuse your debit card primary account number with your checking account number. The primary account number on your debit card is what enables you to make purchases, and it’s the number you’ll store on a website if you set a default payment card. However, your debit card’s primary account number is different than your checking account number. 

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  1. Discover. "What Is a Credit Card Number?" Accessed Aug. 5, 2021.

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