What do credit card numbers mean?

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Credit card numbers actually aren’t random at all.

Credit card numbers each serve a particular function that determines how each transaction will be routed and enhance security.

You probably know your credit card numbers by heart, either in full or the last four digits. But, if you are like most people, you probably have no idea what they mean. The numbers each have a specific identification function either for the bank, the system or you personally. While it is not imperative you know what the numbers mean, understanding the process your information goes through with each credit card transaction is still food for thought.

Unlike other account numbers, like those of the gas or phone company or even department stores, credit cards all use the same number system. In this system, the number and structure of the numbers on the card indicate what kind of card it is and to whom it belongs.

Credit card numbers breakdown

The first number on your credit card is called the Major Industry Identifier (MII) and notes the system that your card belongs to.

  • Number 3 denotes an American Express
  • Number 4 denotes a Visa
  • Number 5 denotes a Mastercard
  • Number 6 denotes a Discover credit card

Within each card system is a structure that is unique to that credit card company. For example:

  • On American Express cards, the third and fourth digits are the type and currency, the fifth through the eleventh digits are the account number, the twelfth through the fourteenth digits are the cards number within that particular account and the fifteenth digit is the check number.
  • A Visa uses digits two through six for the bank number, the seventh digit through the twelfth or the fifteenth are the account number and digit thirteen or sixteen is the validator number.
  • Mastercard uses digits two through six as account numbers depending on the length it can be digits two and three or two through four or two through five or six. After the bank number, the digits that follow up to the fifteenth are the account number and the sixteenth digit is the validator number.

Compare credit cards

Name Product Filter values Rewards Purchase APR Annual fee
Citi Rewards+℠ Card
Earn 2x points at supermarkets and gas stations on up to $6,000 annually, then 1x points after that and on all other purchases
0% intro for the first 15 months (then 14.99% to 24.99% variable)
$0
The only credit card that automatically rounds up to the nearest 10 points on every purchase - with no cap.
Blue Cash Everyday® Card from American Express
2% at US gas stations and select US department stores, 3% at US supermarkets on up to $6,000 per year, then 1% after that and on all other purchases
0% intro for the first 15 months (then 14.49% to 25.49% variable)
$0
Earn a $150 bonus statement credit after you spend $1,000 on purchases in the first 3 months. Rates & fees
CardMatch™ from creditcards.com
See terms
See issuer's website
See terms
Can't decide on a card? Get personalized credit card offers with CardMatch™.
Capital One® VentureOne® Rewards Credit Card
1.25x miles on all purchases
0% intro for the first 12 months (then 13.49%, 19.49% or 23.49% variable)
$0
Earn 20,000 bonus miles once you spend $1,000 on purchases within the first 3 months from account opening.
Citi Simplicity® Card
N/A
0% intro for the first 12 months (then 16.24% to 26.24% variable)
$0
Enjoy one of the longest intro APRs on balance transfers, no late fees, no penalty rate and no annual fee.

Compare up to 4 providers

Bottom line

While it is more important to know where you are spending your money than the function of your credit card numbers, it is helpful to understand the complexities of the credit card system. Once you realize how much effort has gone into ensuring security and efficiency you will have more appreciation for your card.

If you’re looking for a new card, make sure to compare your credit card options to find the best fit for your wallet.

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