Credit card numbers mean different things, depending on where they fit the pattern on your card. Here’s what each section of your credit card number means.
When we’re typing the numbers to buy something online, however, we can start to wonder about things like, “What do all these numbers mean?” or “Why are there so many numbers?”
We have the answers here.
First, let’s talk about why there are so many numbers. Your credit card may have as many as 16 digits. A trillion is just a 1 with 12 zeros after it, which would be far more than enough to give every card in the world a unique number. Why so many digits, then?
The answer to this mystery is that the numbers mean different things, depending on where they fit the pattern on your card. Here’s what each section of your credit card number means.
See related: How do credit cards work?
Major industry identifier (MII)
The first number on your credit card signifies your type of card. It’s known as the major industry identifier (MII). For example, if you have a Visa card, your credit card number starts with the number 4.
Here are the nine MII numbers:
2: Airlines and financial
3: Travel and entertainment, including American Express
8: Health care and communications
See related: Visa vs. Mastercard
Card issuer numbers
Banks use up to the next five numbers to identify the credit card company or issuer. American Express specifies the type of card and currency using digits three and four.
Your account number
The remaining numbers, except for the last digit, are your account number and are specific to you. When you get a new credit card number – for example, when your card is lost – only these numbers and the last digit will change.
Final number determined by formula
The last number on your credit card is special. It’s the only number that is determined by a formula, called the Luhn algorithm, using the preceding numbers on your card.
If you mistype one number on your credit card when you are entering it online, an online validator knows you have not entered a valid credit card number because the number won’t be correct according to the Luhn algorithm.
That’s good for you because you know immediately that you should recheck the number – instead of finding out later when your purchase is declined.
See related: 7 reasons your credit card is blocked
There’s one more set of numbers on your card – the CVV, or card verification value.
If you have a Visa, Mastercard or Discover card, the CVV has three digits and is on the back of your card, on the right side of your signature strip area.
On an American Express card, the CVV has four digits and is on the front of the card, just above and to the right of your credit card number.
Your CVV is intended to prove to online merchants that you actually have the card. Someone who stole your credit card number but not the CVV and the expiration date would not be able to make purchases online. Be very careful who sees your physical credit card or where you enter your account number, including your expiration date and CVV.
Don’t confuse your PIN, or personal identification number, with your CVV. Your PIN is the number you use at an ATM, when getting a credit card cash advance or when making an in-person purchase with a debit card. Never enter your PIN in place of the CVV.