Have you ever wondered how many digits are in a credit card number? We’ve got the answer, along with some other interesting credit card facts.

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## Credit Card Basics

There are generally two types of credit cards out there: personal and business. Each type of credit card has different benefits, but both types usually have a 16-digit credit card number. The number of digits in a credit card number can vary, though, depending on the type of credit card.

### What is a credit card number?

Credit card numbers are generated according to a specific algorithm. The first six digits of a credit card number are known as the issuer identification number (IIN), sometimes referred to as the bank identification number (BIN). These identify the institution that issued the card. The next nine digits are individual account identifiers. The final digit is known as a check digit, and is used to verify the validity of the credit card number.

### How is a credit card number generated?

Credit card numbers are generated according to a specific mathematical formula that is known to the issuer of the card. This formula is known as the Luhn algorithm, and it was developed by IBM scientist Hans Peter Luhn in 1954.

The Luhn algorithm is used by credit card issuers to generate credit card numbers that can be easily validated. It is also used to verify the accuracy of a credit card number when it is typed into a system or scanned.

When a credit card number is generated, the issuer will start with a primary account number (PAN) that is Issuer Identification Number (IIN). The IIN consists of the first six digits of the PAN, and it identifies the institution that issued the card. The next nine digits of the PAN are known as the individual account identifier, and they are used to uniquely identify the cardholder. The final digit of the PAN is known as the check digit, and it is used to validate the accuracy of the PAN.

The check digit is calculated using a specific formula, and it ensures that no two credit cards have the same number. If a credit card number is typed into a system or scanned, and the check digit does not match what was calculated using the Luhn formula, then it is likely that the number has been entered incorrectly or that it has been printed incorrectly.

## The Length of a Credit Card Number

A credit card number is typically composed of 16 digits. The first six digits of a credit card number are known as the Issuer Identification Number (IIN), also called the bank identification number (BIN). These identify the institution that issued the card. The next nine digits are the individual account identification number, and the final digit is a check digit.

### Visa

A Visa credit card number is composed of 16 digits. The first digit is the major industry identifier (MII), which identifies the industry where the card will be used most. The next six digits are the issuer identification number (IIN), which identify the issuer of the card. The IIN is also used to identify the card type. The last digit is the check digit, which is used to validate the credit card number.

### Mastercard

The credit card number must be between 13 and 16 digits long. The first digit is the Major Industry Identifier (MII), which identifies the industry where the card will be used. The next six digits are the Issuer Identification Number (IIN), which identifies the card issuer. The IIN makes up the first part of your credit card number.

The remaining digits, except for the last one, are your account number. The last digit is the check digit, used to detect errors in data entry. Mastercard credit card numbers always start with a 5.

### Discover

Discover Card is a credit card issued primarily in the United States. It was introduced by Sears in 1985. Discover Card services are provided by Discover Bank, which also operates the Discover Cashback Bonus and Miles programs.

The standard Discover credit card has 16 digits. The first six digits are the issuer identification number (IIN), which is also called the bank identification number (BIN). The next nine digits are the individual account number, and the final digit is the check digit.

### American Express

An American Express credit card number is 15 digits long. The first digit is 3, followed by a 4 or a 7. The rest of the number is random, but the last digit is always an odd number.

## The Luhn Algorithm

### What is the Luhn algorithm?

The Luhn algorithm, also known as the “modulus 10” or “mod 10” algorithm, is a simple checksum formula used to validate a variety of identification numbers.

The algorithm is in the public domain and is in wide use today. It is not intended to be a secure hash function; it was designed to protect against accidental errors, not malicious attacks.

Most credit cards and many government identification numbers use the algorithm as a simple method of distinguishing valid numbers from mistyped or otherwise incorrect numbers.

The Luhn algorithm is used by some banks to verify the accuracy of credit card numbers. All major credit cards use numbers that conform to the Luhn formula. The Luhn formula is also used by some airlines to identify potential flight irregularities.

### How does the Luhn algorithm work?

The Luhn algorithm is a check-digit formula used to verify the accuracy of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identification Numbers (NPI), and Individual Taxpayer Identification Numbers (ITIN). The algorithm was developed by German mathematician Hans Peter Luhn in 1954.

The Luhn algorithm uses a simple mathematical formula to validate identification numbers. First, the algorithm discounts every other digit, beginning with the second-to-last digit and working backwards. Second, it sums the digits that were not discounted. Finally, if the sum is a multiple of 10, the identification number is valid; otherwise, it is invalid.

The Luhn algorithm can be used with any identification number that consists of a series of digits; however, it is most commonly used with credit cards and other financial account numbers. When used to validate credit card numbers, the algorithm can help to prevent accidental errors and deter intentional fraud.

## Conclusion

Based on the information above, we can conclude that a credit card number consists of anywhere from 13 to 16 digits. The vast majority of cards (95%) have 16 digits, while the remaining 5% have 15 or 14.