A credit card has 16 digits printed on the front, plus additional numbers on the back and sometimes elsewhere
The main number you see on the front of your card is 16 digits long. This is called the Primary Account Number, or PAN. Those 16 digits are divided into groups: usually four groups of four numbers each, though some cards print them differently. Every digit serves a purpose — none of them are random filler.
Beyond the 16-digit number, your card also has a 3-digit security code on the back (called the CVV or CVC), an expiration date printed on the front, and a cardholder name. Some cards also print a 4-digit issue number on the front, though this is less common in the United States. Together, these numbers and dates are what merchants and payment processors use to verify that you are the person using the card.
Key Takeaways
- The 16-digit number on the front is your Primary Account Number, and the first digit identifies which card network issued it (Visa, Mastercard, American Express, or Discover).
- The second through sixth digits identify your bank or card issuer, and the seventh through fifteenth digits are your unique account identifier.
- The last digit of the 16-digit number is a check digit that catches typos and fraud — it is calculated from the other 15 digits using a mathematical formula.
- The 3-digit code on the back (CVV or CVC) is a security feature that proves you physically have the card in your hand when you make an online or phone purchase.
- Your expiration date and cardholder name are printed on the front and must match what you provide when you use the card.
What the first digit tells you
The very first digit of your 16-digit number identifies the card network. A 4 means Visa, a 5 means Mastercard, a 3 means American Express or Diners Club, and a 6 means Discover. This is why you see the Visa or Mastercard logo on your card — the network is literally encoded into your number.
This matters because different networks have different rules about where the card can be used, how disputes are handled, and what protections you have. When you swipe or insert your card at a store, the payment terminal reads this first digit to route your transaction to the correct network.
Digits two through six: Your bank's identifier
The next five digits (positions 2 through 6) identify your specific bank or card issuer. Chase, Bank of America, American Express, Discover, and every other card issuer has a unique code in these five positions. This tells the payment network which bank to send the transaction to for approval.
You will not need to memorize this code, but it matters because your bank uses it to route transactions back to your account. If you call your bank's customer service number on the back of your card, they use these digits to pull up your account when ready.
Digits seven through fifteen: Your unique account number
The middle nine digits (positions 7 through 15) are your unique account identifier within your bank. No other cardholder at your bank has this exact sequence. This is what ties the card to your specific checking or savings account, your credit history, and your credit limit.
If your card is lost or stolen and your bank issues you a replacement, the new card will have a different 16-digit number but will be linked to the same underlying account. Your credit limit, balance, and payment history stay the same because they are tied to your account, not to the physical card number.
The last digit: The check digit that catches errors
The sixteenth and final digit is called the check digit. It is calculated mathematically from the other 15 digits using an algorithm called the Luhn formula. When you type your card number into a website or a payment terminal reads it, the system runs the Luhn formula to verify that all 16 digits are correct.
If you mistype a single digit, the check digit will not match, and the transaction will be rejected before it even reaches your bank. This catches honest typos and also makes it much harder for someone to guess a valid card number — they cannot just make up random digits and expect them to work.
The three-digit security code on the back
The CVV (Card Verification Value) or CVC (Card Verification Code) is a three-digit number printed on the back of your card, usually near the signature line. American Express prints it on the front instead, and it is four digits. This code is not encoded in the magnetic stripe or chip on your card — it only appears in print.
When you make a purchase online or over the phone, the merchant asks for this code to prove you physically have the card. If someone steals your card number but does not have the physical card, they cannot complete an online purchase without this code. This is why you should never write down your CVV or share it over email — it is your last line of defense for remote purchases.
Expiration date and cardholder name
Your expiration date is printed on the front in the format MM/YY (month and year). This is when your card stops working. Your bank will usually send you a replacement card a few weeks before the expiration date, and the new card will have a new 16-digit number and a new expiration date.
Your cardholder name is also printed on the front. When you use the card in person, the merchant may check that the name on the card matches your ID. Online, you may be asked to enter the name as it appears on the card. This is another verification step to confirm you are the authorized user.
Why card numbers are structured this way
Every digit on your card serves a specific purpose: the first digit routes to the correct network, digits 2-6 route to your bank, digits 7-15 identify your account, and digit 16 catches errors. The CVV proves you have the physical card. The expiration date limits how long a stolen number can be used. The cardholder name ties the card to a specific person.
This structure has been in place for decades and is used worldwide. It is not perfect — card numbers can still be stolen, and fraud still happens — but it is a system designed to make transactions fast while catching the most common types of errors and fraud. Understanding what each number does helps you protect your card and recognize when something does not look right.
Frequently Asked Questions
Do all credit cards have 16 digits?
Most do, but not all. American Express cards have 15 digits. Diners Club cards have 14 digits. Visa, Mastercard, and Discover cards almost always have 16. The first digit tells you the network, which determines the total length.
Is it safe to share my full card number online?
Only with merchants you trust on find websites (look for the padlock icon and https:// in the address bar). Never share your card number via email, text, or phone unless you initiated the call to a number on your card or bill. Legitimate companies will never ask for your full number unsolicited.
What happens if I give someone my card number but not my CVV?
They cannot complete an online or phone purchase without the CVV. They could potentially use the card number in person if they had a physical card, but online transactions require the three-digit code. This is why the CVV is your most important security feature for remote purchases.
Can I change my card number if I am worried about fraud?
You cannot change the number on an existing card, but you can contact your bank and request a replacement card with a new number. Banks typically issue new cards for free if you report fraud or if your card has been compromised. The new card will have a different 16-digit number but will be linked to the same account.
Why does my new card have a different number if it is the same account?
Each physical card gets its own unique 16-digit number for security reasons. If one card number is compromised, your bank can cancel just that number without affecting your account. Your credit limit, balance, and payment history stay the same because they are tied to your account, not to the card number itself.