How Many Numbers Are on a Credit Card?

Daniel Bagley
A stack of credit cards
Reading Time: 4 minutes

How Long Is a Credit Card Number?

Credit cards have a 16-digit number, which appears in four-digit increments on the front or back of the card. There are some exceptions. Visa has a 19-digit card, which is the maximum number allowed by the International Organization for Standardization (ISO). American Express has a 15-digit card, while Visa, Maestro, and Diners Club have some cards with 12 to 14 digits.

Additionally, all cards have a four-digit expiration date, and a three-digit security code. Some credit cards have a four-digit pin, but it is not featured on the card.

When you look at it from left to right, your credit card number indicates the issuer, then the cardholder, and then the final digit verifies the validity of the card.

First Digits: Credit Card Issuer Identifier

The first six digits on a card identify the issuer. The first digit is the Major Industry Identifier (MII). In other words, the first digit identifies the primary purpose of the card, therefore what type of card it is:

2: Airlines and other industry; Mastercard

3: Travel and entertainment; American Express

4: Banking and financial; Visa

5: Banking and financial; Mastercard

6: Merchandising and banking/financial: Discover

Other MIIs between 0-9 are very industry-specific — 0 for the ISO, 1 for airlines, 7 for petroleum, 8 for healthcare and telecommunications, while 9 is for other various industries.

Next after the MII comes 5 digits that, together with the MII, specifically identify the credit card issuer. For Visa the Issuer Identification Number (IIN) will always start with 4 and will be followed by five more digits; for American Express, you’ll see 34 or 37, followed by four more digits; for Mastercard, 51-55, followed by four digits; for Discover, 6011, followed by two more digits.

Personal Identifiers

The digits following the Issuer Identifier are used to identify the unique cardholder. All told, there won’t be more than 12 personal account digits on any card, because the maximum number of digits on a card is 19.

Check Digit

Otherwise known as check number or checksum, the final digit on your card validates all of the other numbers. To do this, card issuers use the Luhn algorithm to assign the final number.   When the final number correctly fits the algorithm, and merchant systems apply a simple formula to your credit card number, and get an answer divisible by 10. This makes it fast and easy to electronically verify credit card purchases, so you aren’t stuck waiting every time you try to complete a transaction.

Here’s what happens: you scan a credit card or input the digits online to make a purchase; your credit card number goes directly to a processor; the processor verifies that your card number satisfies the Luhn algorithm; if all other information checks out, the transaction is approved. The final digit, the check digit, is always the key that completes the sequence necessary for the credit card number to satisfy the Luhn algorithm.

Credit Card Expiration Date

The expiration date is a set of four digits that tells you when you’re required to get a new card. The date usually appears below the card number and consists of two digits representing the month and two digits representing the year year your card will expire. This means your card will be valid until midnight on the last day of the month of expiration.

The expiration date adds an extra level of fraud protection and ensures you’ll get a new card before yours physically deteriorates. It also allows card issuers to provide you with new and improved cards incorporating better security or other features. In the most recent case, they rolled out the EMV chip cards.

Most card issuers automatically send you a new card before yours expires. You’ll need to make sure to change any recurring payment accounts to reflect the information on your new card. Merchants to whom you make recurring payments can sign up for the account updater service, which automatically gives them your new card information, but they have to pay for the service. Check with your recurring payment accounts to see whether they’re enrolled.

Four-Digit CVV Security Code

The Card Verification Value (CVV) code is an additional and final security measure that helps prevent fraud. For Visa, Mastercard, and Discover, you’ll find a three-digit CVV printed on the back of your card by the signature panel. For American Express, you’ll find a four-digit Card Identification (CID) code on the front, just above and to the right of the card number.

Merchants aren’t technically allowed to store your CVV, but they can store your credit card number for later purchases. If and when a data breach occurs and hackers steal credit card numbers, they won’t get your CVV. The CVV is physically attached to your card. If all goes as planned, no one can find it in a database. The only time your CVV could end up in the wrong hands is if you willingly give it to somebody without knowing they plan to use it fraudulently.

Furthermore, some merchants automatically mark a card as valid once you provide the CVV. If someone gets a hold of your credit card number, they may seek to use it on merchant sites where you already have an account.

Customer Service Phone Number

Your credit card will have a phone number on the back to call in case of any issues. The number is located beneath the signature strip.

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