Credit card numbers are 13 to 19 digits long, most commonly 16

A standard credit card number contains 16 digits. Visa, Mastercard, and Discover all use 16-digit numbers. American Express uses 15 digits. Some specialty cards and older cards may have 13 or 14 digits, and certain business or international cards can reach 19 digits, but these are less common.

The digits are not random. Each one serves a specific purpose in the card's structure. The first digit identifies the card network — Visa cards start with 4, Mastercard with 5, American Express with 3, and Discover with 6. The next several digits identify your bank and account type. The final digit is a check digit, calculated using the Luhn algorithm, which card readers use to verify the number is valid before processing a transaction.

When you see a credit card number printed on a statement or online, it is usually displayed with spaces or dashes for readability — for example, 4532 1234 5678 9010 — but the spaces are not part of the number itself.

Key Takeaways

  • Most credit cards have 16 digits, but American Express has 15 and some specialty cards have 13, 14, or 19.
  • The first digit identifies the card network: 4 for Visa, 5 for Mastercard, 3 for American Express, 6 for Discover.
  • The last digit is a check digit that validates the entire number using a mathematical formula.
  • Spaces or dashes in printed card numbers are for readability only and are not part of the actual number.

Why the length varies by card type

Different card networks set their own standards. Visa, Mastercard, and Discover settled on 16 digits decades ago and have kept that standard. American Express chose 15 digits when it launched its card program and has maintained that length. The difference does not affect how the card works — it is simply the standard each network uses.

Older cards, particularly those issued before the 1990s, sometimes had 13 or 14 digits. If you have an old card statement or receipt, you may see these shorter numbers. They are no longer issued by major networks.

Some business cards, corporate purchasing cards, and cards issued internationally may have 19 digits. These are designed for specific use cases and are not common in consumer wallets. When you enter a card number online or at a terminal, the system is programmed to accept the length that matches the card network.

How the card number breaks down

A 16-digit Visa card number is structured like this: the first digit (the Major Industry Identifier) identifies Visa. Digits 2 through 6 (the Issuer Identification Numberaccount number — the unique identifier for your account at that bank. The 16th digit is the check digit.

The check digit is calculated from the other 15 digits using the Luhn algorithm, a formula that catches most typos and transcription errors. When you enter your card number at a checkout or online, the system runs the Luhn check before sending the number to the payment processor. If the check fails, the system rejects the number immediately, even before contacting your bank.

American Express uses a similar structure but compresses it into 15 digits. The first digit is always 3, digits 2 and 3 identify American Express as the issuer, digits 4 through 14 are the account number, and digit 15 is the check digit.

What happens when you enter your card number

When you type or swipe your card number, the merchant's system first validates the length — it checks whether the number has the correct number of digits for the card type you selected. If you say it is a Visa but enter 15 digits, the system will reject it. If the length is correct, the system runs the Luhn check.

Only after both checks pass does the system send the number to the payment processor. The processor then contacts your bank to verify the account exists and has available credit. At no point does the merchant store the full card number — payment card industry standards require that merchants delete it after the transaction completes.

If you are entering your card number manually and make a typo, the Luhn check will catch most single-digit errors and transposed digits. This is why the system sometimes rejects a number you are certain is correct — you may have mistyped one digit, and the check digit no longer matches.

Why card numbers are not the same as account numbers

Your card number and your bank account number are different. Your card number is issued by your bank specifically for credit card transactions. Your account number is the underlying account at the bank that the card draws from. If you close the card and open a new one, you get a new card number, but your underlying account remains the same.

This separation exists for security. If your card number is compromised, your bank can issue a new card number without changing your account. Merchants and payment processors see only the card number, not your account number. Your bank keeps the account number private and uses it only for internal record-keeping and transfers between accounts.

When you set up automatic payments or recurring charges, you provide your card number, but the merchant does not use it to access your bank account directly. Instead, the merchant stores a token — a substitute identifier — that the payment processor uses to charge your card each month. The actual card number is never stored on the merchant's system.

How to protect your card number

Your card number is sensitive information. Anyone with your full number, expiration date, and CVV (the three-digit code on the back) can make purchases in your name. Protect it the same way you would protect cash.

Do not share your card number over email, text, or phone unless you initiated the contact and you are certain you are speaking to your bank or a merchant you trust. Do not photograph your card or store images of it on your phone or computer. When entering your number online, check that the website uses HTTPS (you will see a padlock icon in the address bar) and that you are on the merchant's official site, not a phishing copy.

If you notice a transaction you did not make, contact your bank immediately. Most banks cover fraudulent charges, but you must report them within a specific window — usually 60 days from the statement date. The sooner you report it, the faster the investigation moves.

Frequently Asked Questions

Why does American Express have 15 digits instead of 16?

American Express set its own standard when it launched its card program and has kept it for consistency. The 15-digit format works just as well as 16 digits — it is simply a different choice by a different company. Amex cards are processed the same way as Visa or Mastercard; the system just expects a different length.

Can I use a card number with spaces or dashes?

Spaces and dashes are for readability only. When you enter your card number online or at a terminal, you can type it with or without spaces — most systems accept both and ignore the spaces automatically. The actual card number contains only the 16 (or 15, or 13, or 19) digits.

What does the first digit of my card number mean?

The first digit identifies the card network. Visa cards start with 4, Mastercard with 5, American Express with 3, and Discover with 6. This digit is part of the Major Industry Identifier standard and tells payment systems which network to route the transaction through.

If I memorize my card number, is it safe?

Memorizing your card number is safer than writing it down or storing it in your phone, but it is not necessary for everyday use. You do not need to memorize it — your physical card or your bank's app will have the number when you need it. If you do memorize it, keep the expiration date and CVV separate in your memory.

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

Yes. If your card is lost, stolen, or damaged, your bank issues a new physical card with a new card number. Your underlying account stays the same, but the card number changes. You will need to update any recurring payments or subscriptions that use the old card number.