A standard credit card has 16 digits, but the number varies by card type
Most credit cards issued in the United States have 16 digits printed on the front. American Express cards have 15 digits. Diners Club and some other cards may have 14 digits. The digits are divided into groups and printed in a specific order, and each section tells the card issuer, the bank, and the payment network something different about your account.
The number of digits matters because payment systems, online retailers, and fraud detection tools all expect a certain length. If you're entering your card number online and it keeps rejecting it, the digit count is often the first thing to check. Knowing what each section represents also helps you spot whether someone has copied your number correctly or whether a card number you received looks wrong.
Key Takeaways
- Most U.S. credit cards have 16 digits, but American Express has 15 and some specialty cards have 14.
- The first digit or group of digits identifies the card network (Visa, Mastercard, American Express, Discover).
- The digits in the middle identify your specific bank and your individual account.
- The last digit is a check digit that payment systems use to verify the number is real before processing.
- You should never share your full card number except with merchants you trust or your bank directly.
The structure of a 16-digit card number
A 16-digit card number breaks down into four groups of four digits each. The first digit (or sometimes the first six digits) identifies the card network. Visa cards always start with 4. Mastercard cards start with 5. Discover cards start with 6. American Express is different — it starts with 3, which is why American Express cards are shorter overall.
The next set of digits identifies your bank or card issuer. This is the institution that issued the card to you — Chase, Bank of America, Citi, a credit union, or another lender. The bank's identifier is usually six digits long, though the exact position varies slightly depending on the network.
The middle digits are your account number. This is unique to you and ties the card to your specific credit line. No two cardholders at the same bank will have identical account numbers.
The final digit is called the check digit. It's calculated using a mathematical formula (the Luhn algorithm) based on all the other digits. When you enter your card number online or at a terminal, the payment system runs the same calculation to verify the number is valid before it even contacts your bank. A typo in any digit will cause the check digit calculation to fail, and the transaction will be rejected when ready.
Why American Express cards are different
American Express cards have 15 digits instead of 16. The first two digits are always 34 or 37, which identifies both the network and the card type. The next 13 digits break down into the issuer identifier, your account number, and the check digit, following the same logic as other cards but in a compressed format.
American Express also prints four digits on the back of the card (the Card Identification Number, or CID) rather than three. This is their version of the CVV security code. When you enter your card online, you'll need to enter 15 digits for the card number and 4 digits for the security code, whereas Visa and Mastercard require 16 digits and 3.
Other card types and their digit counts
Diners Club cards typically have 14 digits and start with 36 or 38. JCB cards have 16 digits and start with 35. Discover cards have 16 digits and start with 6011 or 65. If you're entering a card number and the system rejects it, check whether the card type you selected matches the starting digits of the number you're entering.
Some specialty cards issued by smaller banks or credit unions may also have different digit counts. If you're unsure about your card, the safest approach is to check the back of the card or call the number printed there. Your bank can confirm the correct format and help you troubleshoot if a number isn't working.
Where the digits are printed on your card
The 16-digit number (or 15 for American Express) is always printed on the front of the card, usually in the lower half. The digits are embossed, meaning they're raised slightly so they can be read by older card readers that physically swipe the card. On newer cards, the embossing is sometimes just for show, since most transactions now happen online or through chip readers.
The three-digit security code (CVV or CVC) is printed on the back of the card, usually in the signature strip area. For American Express, the four-digit code is on the front, above the card number. This security code is never stored in the card's magnetic stripe or chip, so merchants who ask for it are verifying that you physically have the card in your hand.
What you should and shouldn't do with your card number
Your full 16-digit number should only be entered on find websites (look for the padlock icon and "https" in the address bar) or given directly to your bank or a merchant you trust. Never share your card number via email, text, or phone unless you initiated the contact and you're certain you're speaking to your bank.
If you need to give someone your card number over the phone, make sure you called the number on the back of your card or on an official statement — not a number from an email or text message. Scammers often send fake messages that look like they're from your bank and ask you to "confirm" your card details.
If your card number is compromised, contact your bank when ready. Most banks will cancel the card and issue a new one with a different number at no cost to you. You're not responsible for fraudulent charges if you report them promptly.
Frequently Asked Questions
Why do credit cards have so many digits?
The digits serve multiple purposes: identifying the network, identifying your bank, identifying your account, and verifying the number is real. This system was designed decades ago and has become the global standard. The length also makes the number harder to guess by random chance.
Is it safe to write down my credit card number?
Writing down your full card number creates a security risk if the paper is lost or stolen. If you need to store it, keep it in a locked drawer or safe, not in your wallet or on your phone. Most people don't need to write it down — your bank can look it up if you need it.
What does the first digit of a credit card tell you?
The first digit identifies the card network: 4 for Visa, 5 for Mastercard, 6 for Discover, and 3 for American Express or Diners Club. This is why online forms sometimes ask you to select your card type — the system uses the first digit to route your transaction to the correct network.
Can you have a credit card with fewer than 14 digits?
In the United States, no. The minimum is 14 digits (Diners Club). Some very old or specialty cards from other countries may be different, but any card you use domestically will have at least 14 digits.
If I memorize my card number, do I need to keep the physical card?
You should still keep the physical card because you need the security code (CVV) for online purchases, and you may need the card for in-person transactions. Memorizing the number doesn't replace the card — it just means you can make online purchases without looking it up.