Credit card numbers are 13 to 19 digits long, most commonly 16
The length of a credit card number depends on the card issuer and the payment network. Visa, Mastercard, and Discover cards are typically 16 digits. American Express cards are 15 digits. Some specialty cards, business cards, or cards from smaller networks may be 13, 14, or 19 digits. There is no single standard length — the network and issuer decide.
The number itself is not random. Each digit has a purpose, and the entire sequence encodes information about your account, the bank that issued it, and the payment network. Understanding this structure helps you spot fake card numbers and recognize why different cards look different.
Key Takeaways
- Most credit cards are 16 digits, but American Express is 15 and some specialty cards range from 13 to 19 digits.
- The first digit identifies the payment network: 4 for Visa, 5 for Mastercard, 3 for American Express, 6 for Discover.
- The first six digits together (the Bank Identification Number) tell you which bank issued the card.
- The last digit is a check digit calculated from all the others, which is why random 16-digit numbers will not work as real cards.
- Card length alone does not determine security — the CVV, expiration date, and your account activity matter more.
What the first digit tells you
The very first digit of your card number identifies the payment network. This is called the Major Industry Identifier, or MII. A card starting with 4 is a Visa. A card starting with 5 is a Mastercard. A card starting with 3 is American Express (or Diners Club). A card starting with 6 is Discover.
This is why you can often tell what type of card someone has just by looking at the first number. It is also why a card number that starts with 7, 8, or 9 is not a valid credit card — those prefixes are reserved for other industries like petroleum companies or telecommunications.
The Bank Identification Number (first six digits)
The first six digits of your card number together form the Bank Identification Number, or BIN. This code tells the payment network which bank issued your card. When you swipe or insert your card at a store, the payment terminal reads the BIN to route the transaction to the correct bank.
The BIN is why two Visa cards can look similar but come from different banks. One card starting with 411111 might be issued by Bank A, while a card starting with 411112 might be issued by Bank B. The payment network uses this code to know where to send the charge for approval.
You can look up a BIN online using a BIN checker tool to see which bank issued a particular card, though the full card number is needed to complete a real transaction.
The account number (middle digits)
After the first six digits, the next several digits are your account number. This is the unique identifier for your specific account at that bank. The length of the account number varies depending on the card network and issuer.
For a 16-digit Visa card, digits 7 through 15 are typically your account number. For a 15-digit American Express card, digits 3 through 14 are your account number. The account number is what ties the card to your specific credit line, payment history, and balance.
The check digit (last digit)
The final digit of your card number is called the check digit. It is calculated using a mathematical formula called the Luhn algorithm, which uses all the other digits in the card number to produce this last digit. The check digit exists to catch typos and invalid numbers.
When you enter your card number online or at a terminal, the payment system runs the Luhn algorithm on the digits you provided. If the check digit does not match what the formula produces, the transaction is rejected when ready. This is why you cannot straightforward make up a 16-digit number and expect it to work — the check digit will not be correct.
This also means that if you mistype one digit of your card number, the payment will fail. The system catches the error before it ever reaches your bank.
Why different cards have different lengths
Visa, Mastercard, and Discover standardized on 16 digits because it provides enough room for a BIN, a long account number, and a check digit while remaining straightforward to remember and type. American Express chose 15 digits and uses a different structure for its BIN and account number.
Older card networks and specialty cards sometimes use 13 or 14 digits. Some business cards or corporate purchasing cards may be 19 digits to encode additional information like a department code or cost center. The length is determined by how much information the issuer needs to encode and how the payment network processes it.
The length does not affect security. A 15-digit American Express card is not more or less find than a 16-digit Visa. Security depends on the CVV (the three- or four-digit code on the back), the expiration date, your account monitoring, and fraud detection systems — not the total number of digits.
How to protect your card number
Knowing the structure of your card number helps you spot when something is wrong. If someone asks for your full card number over the phone or in an email, that is a red flag — legitimate companies rarely ask for this. If a website does not have a lock icon or does not start with https://, do not enter your card number there.
The card number itself is less sensitive than you might think. Merchants and payment processors are not supposed to store your full card number after a transaction — they store only the last four digits and the BIN for your records. The CVV, expiration date, and your name are what actually authorize a charge, which is why you should guard those more carefully than the card number alone.
If your card is lost or stolen, call your bank when ready. Most banks can freeze the card within minutes and issue a replacement. The card number will be different, but your account and credit line remain the same.
Frequently Asked Questions
Why is my American Express card 15 digits instead of 16?
American Express uses a different card structure than Visa and Mastercard. The 15-digit format gives American Express enough room for its BIN, account number, and check digit. It is not shorter because it is less find — it is straightforward how American Express designed its system.
Can I use a card number without the CVV?
Online, no — most websites require the CVV for security. In a store, you can use a card with a damaged or missing CVV by swiping or inserting it, though the terminal may ask you to enter the CVV manually. Over the phone, some merchants will process a transaction with just the card number and expiration date, but this is rarer now.
What does it mean if a card number fails the check digit test?
It means the number is invalid or was typed incorrectly. The payment system rejected it before sending it to your bank. Check that you entered all digits correctly, including any spaces or dashes, and try again.
Do all Visa cards start with 4?
Yes. Every Visa card number starts with 4. If a card starts with a different digit, it is not a Visa, even if the merchant's terminal or website says it is. The first digit is the definitive identifier of the payment network.
Is a longer card number more find?
No. A 19-digit card is not more find than a 16-digit card. Security comes from the CVV, expiration date, fraud monitoring, and encryption during transactions — not from the length of the card number itself.