What do credit card numbers mean?

When you’re approved for a credit card and receive it in the mail, it comes with a string of numbers displayed on the front or back of the card. This is your credit card number that identifies your account. Typically, the number is 16 digits in length, though it can be shorter or longer depending on the card issuer. For example, American Express credit card numbers are 15 digits long.

Credit card numbers follow a set standard, and each digit serves a specific purpose in identifying the card issuer and the account holder.

Find your perfect card in 30 seconds. Check your approval odds so you can shop smarter.

Your credit card number

A credit card comes with a set of digits unique to you. The numbers identify the bank or credit card issuer and include information about your account. It also serves as an identifier to prevent credit fraud and theft.

The first number: Major Industry Identifier

The first digit in your credit card number is known as the Major Industry Identifier (MII). The MII identifies which industry or category the credit card issuer belongs to.

The first six or eight numbers

The first six or eight digits are called the Issuer Identification Number (IIN). It’s sometimes called the Bank Identification Number (BIN). The IIN or BIN includes the Major Industry Identifier. The remaining string of numbers in the IIN further identifies the bank or financial institution that issued the credit card.

In 2016, the International Organization for Standardization (IOS) approved new standards for Issuer Identification Numbers to allow the assigning of six or eight-digit IINs. The move was a preventative measure to avoid a shortage of available numbers as more card issuers emerged.

The chart below shows the IIN ranges for some of the more popular credit card issuing networks.

IIN or BIN number ranges vary in length. For example, Visa cards are identified by starting with the number “4.” Mastercard credit cards are identified by multiple number strings starting with “2221-2720” or “51-55.”

The account number

The remaining digits after the IIN, except the last digit, identify the cardholder’s individual account. Your card account number is between nine and 12 digits, depending on the card issuer.

The check digit

The last digit of your credit card number is known as the check digit or check sum. Payment processors use this number to verify if a credit card is valid. A check digit is created using a formula known as the Luhn Algorithm, developed by IBM engineer Peter Luhn in 1954.

If someone enters an incorrect number during payment, the error is immediately detected through the check digit’s algorithm.

The security number or CVV

Credit cards come with other identifying markers besides a credit card number. They also come with a card verification value (CVV) that’s used as an added security measure. Typically, it’s located on the back of a credit card, but some issuers include it elsewhere. For example, American Express credit cards have CVV codes on the front.

Card issuers include a CVV as an added security measure to reduce unauthorized transactions. If you’re shopping only or making purchases with just the credit card number, you’ll probably be required to give your CVV code for verification. Since merchants aren’t allowed to store CVV numbers, it’s much harder for cyber thieves to get that information.

The expiration date

Credit cards come with an expiration date, usually two to four years after being issued. The expiration date is usually listed as four digits — two digits for the month and two digits for the year it expires. If the number listed is 05/26, the expiration date is May 2026.

There are many reasons that cards come with expiration dates, including the following:

• They work as another security measure
• Cards suffer from wear and tear over time and may eventually be unusable
• Changes in card technology mean a card can become obsolete