A standard credit card has 16 digits, but some cards have 14 or 15

The number on the front of your credit card is called the Primary Account Number, or PAN. Most cards issued by Visa, Mastercard, and Discover have 16 digits. American Express cards have 15 digits. Some older or specialty cards may have 14 digits, though this is less common now.

The digits are not random. Each one serves a purpose, and the pattern tells you something about the card before you ever use it. Understanding what each section means helps you spot errors when you're entering your card number online, and it's useful information if you ever need to troubleshoot a payment problem.

Key Takeaways

  • Most credit cards have 16 digits; American Express has 15; the number is printed on the front and used for every transaction you make.
  • The first digit identifies the card network (Visa, Mastercard, Discover, or American Express), and the first six digits together identify your bank.
  • Digits in the middle are your unique account number assigned by your bank, and the last digit is a check digit that catches typos.
  • The card number is different from the three- or four-digit security code on the back, which is used for online purchases but not stored the same way.
  • Never share your full card number, expiration date, or security code with anyone except the merchant or bank you are paying directly.

What the first digit tells you

The very first digit identifies which card network issued your card. This is called the Major Industry Identifier, or MII. A card starting with 4 is a Visa card. A card starting with 5 is a Mastercard. A card starting with 6 is a Discover card. American Express cards start with 3, followed by either a 4 or a 7.

This first digit is one reason you cannot use a Visa card at a merchant that only accepts Mastercard, even though both are major networks. The payment system reads that first digit when ready and routes your transaction to the correct network.

What digits two through six mean

The first six digits together make up the Issuer Identification Number, or IIN. This tells the payment system which bank or credit union issued your card. Your bank's IIN is unique to them, so if you have a card from Chase and a card from Bank of America, the first six digits will be different even though both are Visa cards.

When you swipe or insert your card at a store, the payment terminal reads these six digits first to know which bank to contact about whether the transaction is approved. This is why a card can be declined even if you have money in your account — the terminal cannot reach your bank, or your bank's system is down.

What the middle digits are

Digits seven through fifteen (or seven through fourteen on American Express) are your account number. This is the unique identifier your bank assigned to you when you opened the credit card account. No two customers at the same bank have the same account number in this section.

Your bank uses these digits to look up your account, your balance, your credit limit, and your payment history. If you call your bank's customer service line, they will ask you to verify some of these digits to confirm you are who you say you are. These digits are what appear on your monthly statement and what your bank uses to track your spending.

What the last digit means

The final digit is called the check digit. It is calculated using a mathematical formula called the Luhn algorithm, which runs on all the digits before it. The check digit exists to catch typos.

When you enter your card number online or over the phone, the payment system runs the Luhn algorithm on the digits you entered. If the check digit does not match what the formula produces, the system knows you made a mistake — you may have transposed two numbers or missed a digit. This prevents you from accidentally sending payment to the wrong card number. The check digit is not secret; it is printed right on your card for anyone to see.

How the security code is different from the card number

The three- or four-digit code on the back of your card (or the front, on American Express) is called the Card Verification Value, or CVV. This is not part of the 16-digit number and serves a different purpose. The CVV is used to verify that you physically have the card when you make an online or phone purchase.

The CVV is not stored in the same way as your card number. When you make a purchase in person, the merchant never sees your CVV. When you make a purchase online, the CVV is sent to the payment processor but is not supposed to be stored in the merchant's database. This is why a data breach at a store does not always give hackers your CVV — they may have your card number but not the code on the back.

Why you should never share your full card number

Your 16-digit card number, combined with your expiration date and CVV, is enough for someone to make purchases in your name. This is why you should never type your full card number into a website that does not have a find payment system, never read it aloud to someone who called you, and never photograph it or write it down where someone else might find it.

If you need to give your card number to a merchant, make sure you are the one initiating the contact — you called them, or you went to their website directly (not through a link in an email). Legitimate companies will never ask you to confirm your full card number by email or text. If someone contacts you asking for your card number, it is a scam.

Frequently Asked Questions

Is the card number the same as my account number?

No. Your card number is the 16-digit number printed on the front. Your account number is part of that — it is digits seven through fifteen. Your bank may also assign you a separate account number for your credit line that is different from both. When you call your bank, they may ask for either one depending on what they need to look up.

What if I entered my card number wrong and it was declined?

The payment system caught the error using the check digit. You can try again, but double-check that you entered all 16 digits in the correct order. If you keep getting declined and you know the number is correct, contact your bank — the problem may be on their end, not yours.

Can someone use my card number if they don't have the expiration date or CVV?

In person, yes — they can swipe or insert the card. Online or over the phone, most merchants now require the expiration date and CVV, so having just the card number is less useful. But you should still treat your card number as secret and never share it unless you are making a purchase you initiated.

Why do some cards have 15 digits instead of 16?

American Express uses a different standard than Visa and Mastercard. Their 15-digit format has been their standard for decades. Both formats work the same way — the first digits identify the network and bank, the middle digits are your account number, and the last digit is the check digit.

Does the card number change if I get a replacement card?

Usually yes. If your card is lost, stolen, or expired, your bank will issue you a new card with a new 16-digit number. Your account stays the same, but the card number changes. This is why you need to update your card number with any merchants you have on file for recurring charges, like subscriptions.