How Long Is a Credit Card Number and How It Works

A credit card number is a 16-digit code that identifies your account and allows you to make transactions.

The number is divided into four parts: the first six digits represent the bank and card issuer, the next six digits are the account number, and the last four digits are the card verification value.

These 16 digits work together to verify your identity and ensure secure transactions.

A credit card number is the set of digits printed on either the front or back of a physical credit card.

Credit card numbers are often 16 digits, but they can be as long as 19 digits or as short as 13.

These numbers are systematically assigned and indicate several things about your credit card type.

A credit card number indicates not only your account number but also the card issuer.

The card's industry affiliation is also shown in the credit card number.

Each digit in a credit card number plays a role in identifying the card.

Your credit card number can be up to 12 digits long, and it's assigned by the financial institution issuing the card.

The account number on your card begins with the seventh digit and ends on the second to last digit. To find it, cross out the first six digits and the last one.

While your credit card number may change if your card is lost or stolen, your account number stays the same.

The first digit of a credit card number is a crucial identifier that tells you the credit card network being used and/or the industry associated with the card. This digit is also known as the Major Industry Identifier (MII).

The first digit can indicate the card network, such as Mastercard (2 or 5), American Express (3), Visa (4), or Discover (6). You can quickly identify the network by looking at the first digit.

Here's a breakdown of the first digit and the corresponding credit card network:

The first digit can also indicate the industry associated with the card, such as airlines (1), banking and financial (4 or 5), or merchandising and banking (6).

The next 6-12 digits of a credit card number are the account number, which identifies the individual credit card account.

This part of the credit card number can vary in length depending on the credit card, but it's typically 9 digits long for a 16-digit number.

The account number is what sets your credit card account apart from others, making it a crucial part of your credit card information.

For example, if your credit card number is a 16-digit number, the account number will be the middle 9 digits.

Your actual credit account number can be up to 12 digits long and identifies you as the owner of the credit card account. Credit card numbers are assigned by the financial institution issuing the card.

The account number on the card begins with the seventh digit and ends on the second to last digit. To find your account number, look at the long number on the front of your card and cross out the first six digits, as well as the last one.

Your credit card number may change if your card is lost or stolen, but your account number stays the same.

Appendix B provides valuable information about credit card number formats and the Luhn Mod-10 algorithm used for validation.

The Luhn Mod-10 algorithm, invented by Hans Peter Luhn in 1954, is a simple formula used to detect single digit errors and most transpositions of adjacent numbers in account numbers.

Here's a step-by-step guide to determining if an account number is Mod-10 compliant: working from the right, double every other number, treat 2-digit numbers as individual digits, add all the numbers together, and check if the result is a multiple of 10.

The algorithm is used in numerous applications, including credit cards, to ensure account numbers are valid and accurate.

If the result of the Luhn Mod-10 algorithm is a multiple of 10, the account number is Mod-10 compliant.

The algorithm is relatively simple and can be applied to any account number to determine its validity.

For example, for the account number 4005550000081019, the computations are shown in the table below.

This table shows the computations for the Luhn Mod-10 algorithm.