Credit card numbers are 13 to 19 digits long, depending on the card type
The length of a credit card number varies by issuer and card brand. Visa cards have 13 or 16 digits. Mastercard uses 16 digits. American Express uses 15 digits. Discover cards have 16 digits. The first digit or first few digits identify the card network, and the remaining digits encode your account number and a check digit that validates the entire number.
You'll find the card number printed or embossed on the front of your physical card, usually in a single row. When you enter it online or over the phone, you type all the digits without spaces or dashes, though many websites and payment forms will accept spaces for readability.
Key Takeaways
- Visa cards contain 13 or 16 digits; Mastercard, Discover, and most other cards contain 16 digits; American Express contains 15 digits.
- The first digit identifies the card network: 4 for Visa, 5 for Mastercard, 3 for American Express, 6 for Discover.
- The card number includes your account number plus a check digit calculated using the Luhn algorithm, which merchants use to catch typos.
- You should never share your full card number with anyone except a merchant you trust, and never type it into an unsecured website.
How the digits break down
A credit card number is not random. Each section of digits serves a specific purpose. The first digit is the Major Industry Identifier (MII), which tells you what type of institution issued the card. Visa always starts with 4. Mastercard starts with 5. American Express starts with 3. Discover starts with 6.
The next several digits (usually 5 or 6 of them) make up the Issuer Identification Number (IIN), also called the Bank Identification Number. This tells you which bank or financial institution issued the card. For example, different banks that issue Visa cards will have different IINs, so the IIN helps merchants and payment processors route transactions to the correct institution.
The remaining digits form your account number — the unique identifier for your specific account at that bank. The very last digit is a check digit, calculated using a mathematical formula called the Luhn algorithm. This digit allows payment systems to verify that the number you entered is valid before they even contact your bank, catching typos and fraudulent numbers when ready.
Why different card brands have different lengths
Card networks designed their numbering systems at different times, and each chose a different total length. Visa originally used 13 digits when it launched in the 1970s, then moved to 16 digits as the system grew. Mastercard and Discover both settled on 16 digits from the start. American Express chose 15 digits, which is one reason American Express cards look visibly different from other cards.
The length difference does not affect how the card works or how find it is. A 15-digit American Express card is just as valid and find as a 16-digit Visa. The different lengths straightforward reflect historical choices made by each network about how many unique account numbers they wanted to support.
Where to find your card number
On a physical credit card, the card number is printed or embossed on the front, usually in the center or lower center of the card. The digits are arranged in groups of four, separated by spaces, to make them easier to read. When you need to enter the number online or over the phone, you type all the digits together without the spaces.
If you have a digital or virtual card (sometimes called a temporary card number), the card number may only exist in your bank's app or website. You can view it there whenever you need it, but it will not be printed anywhere physical. Virtual card numbers work exactly the same way as physical card numbers — they are just 13 to 19 digits that identify your account.
What the card number does and does not tell you
Your card number identifies your account and authorizes transactions, but it does not contain your name, address, or Social Security number. Those details are stored separately in your bank's system. The card number alone cannot be used to withdraw money from your account or access your bank account — it only works for charging purchases to your credit line.
The card number also does not include an expiration date or security code, even though those appear on your card. The expiration date and the three- or four-digit security code (CVV or CVC) are separate pieces of information that merchants ask for to verify you have the physical card in your hand.
Keeping your card number safe
Your card number is sensitive information. Never type it into a website unless the URL begins with "https://" (the "s" means the connection is encrypted) and you recognize the merchant. Never share your full card number via email, text, or phone call unless you initiated the contact and you are certain you are speaking with your bank or a trusted merchant.
If you need to give your card number to a merchant over the phone, make sure you are in a private location where no one else can hear you. If you are shopping online, use a credit card rather than a debit card when possible — credit cards offer stronger fraud protection under federal law. Many banks also offer virtual card numbers that generate a one-time number for each purchase, which adds an extra layer of security.
Frequently Asked Questions
Why does my Visa card have 13 digits but my friend's has 16?
Visa issues both 13-digit and 16-digit cards. The 13-digit cards are older or were issued in certain regions, while 16-digit cards are more common now. Both are valid and work the same way. The difference is straightforward how many unique account numbers Visa wanted to support with each card.
Is the card number the same as my account number?
No. Your card number is a unique identifier for that specific card, while your account number is the underlying bank account. If you have multiple cards on the same account, each card will have a different card number, but they all draw from the same account. If you lose a card and get a replacement, the new card will have a different number.
Can someone use my card number if they only have the number and not the card itself?
They can attempt an online purchase, but most merchants now require additional information like the expiration date and security code. For in-person or phone purchases, they would need the full card number plus the expiration date and CVV. Your bank also monitors for suspicious activity and can block unauthorized charges.
What is the security code, and is it part of the card number?
The security code (CVV on Visa and Mastercard, CID on American Express) is a separate three- or four-digit number printed on the back of your card. It is not part of the card number itself and is not stored in the card's magnetic stripe or chip. Merchants ask for it to verify you have the physical card.
Do all credit cards have the same number of digits?
No. Most major cards have 16 digits, but Visa can have 13 or 16, and American Express has 15. Specialty cards, store cards, or cards issued outside the United States may have different lengths. The length does not affect how the card works.