What do the 15 digit numbers on an American Express number mean ?

Credit cards that are part of the Visa, Mastercard and Discover payment networks have 16 digits, while those on the American Express payment network have only 15. There is also another number on the front or back of your credit card that can be used to authenticate transactions.

What Do All the Numbers on Your Credit Card Mean?

While all the numbers on your credit card can appear random, there is real meaning behind them. For example, if your credit card number starts with 3, then it is always part of the American Express, Diner's Club, or Carte Blanche payment networks. If the card starts with the number 4, it is Visa. Card numbers that start with 5 are part of the MasterCard, while cards that start with 6 are part of the Discover network.

The next five digits can be used to identify the card issuer, such as a bank or credit union, as well as the specific credit card product you are using. For example, all Chase Visa Signature cards such as Chase Sapphire Reserve ® and Chase Freedom Unlimited ® start with the number 414720.

The other 15 or 16 digits are unique and are associated with the cardholder's account number. The last one or two digits are "check digits". Check digits are applied to a formula that helps determine if your credit card number is really valid. With this formula, the computer can quickly determine if a valid credit card number exists.

Credit Card Number versus Account Number

Interestingly, the number on your credit card isn't actually your account number, even though the two are related. Your account number will often appear on your credit card statement, and you will need to refer to it to make a payment. If your card is lost or stolen, you will receive a replacement card with a new credit card number, but your account number will remain the same. In addition, each American Express card has a unique number, even among authorized user cards issued from the same account. Conversely, an authorized user card from another payment network will have the same number when linked to the same account.

What About Those Other Numbers?

Credit cards also have three digit numbers that usually appear on the back of the card in the signature panel. These numbers can be called CVC numbers (Card Verification Code), but also use other names. Its purpose is to provide another level of verification when you make a purchase where the card does not exist, such as a telephone or online transaction. American Express cards also have a four digit number on the front that serves the same purpose, which is called CVV (Card Verification Value).

How to Protect Your Credit Card Number

Now that you know what all these numbers mean, you need to know how best to protect them. First, you should always be careful when taking pictures that show your credit card number. Modern still and video cameras have very high resolutions, and one can enlarge the image to read credit card numbers, even if the card is not very large in the image. If you need to put your credit card in the picture, make sure to cover it
as many numbers as possible. Since the first six digits are not unique to your card, be sure to cover the other nine or ten digits, if not all of them.

You should also avoid writing down your credit card number, as this information can be used fraudulently, much like your real credit card. And if your credit card is lost or stolen, be sure to report it to your card issuer. Most card issuers will send you a replacement card at no charge, and many will send it free by post overnight if you request one.

Now you know what that long credit card number means. The next step is to protect your card and card numbers so this information doesn't fall into the wrong hands.