What do credit card numbers mean?

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.

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Name	Product	Filter values	Rewards	Purchase APR	Annual fee
Blue Cash Preferred® Card from American Express			6% on select US streaming services, 3% on transit and US gas stations, 6% at US supermarkets on up to $6,000 annually, then 1% after that and on other purchases (redeem as statement credit)	0% intro for the first 12 months (then 13.99% to 23.99% variable)	$0 intro annual fee for the first year ($95 thereafter)	Apply now View details	Earn a $300 statement credit after you spend $3,000 in purchases on your new card within the first 6 months. Having 6 months to earn a welcome offer is a rare benefit as most cards give you only 3. Terms apply, see rates & fees	Compare	loading Fetching your data...
Capital One Venture Rewards Credit Card			Earn unlimited 2x miles on every purchase, every day	15.99% to 23.99% variable	$95	Apply now View details	Earn 60,000 bonus miles once you spend $3,000 on purchases within the first 3 months ​from account opening	Compare	loading Fetching your data...
Capital One Quicksilver Cash Rewards Credit Card			Earn unlimited 1.5% cash back on every purchase, every day	0% intro for the first 15 months (then 14.99% to 24.99% variable)	$0	Apply now View details	One-time $200 cash bonus after you spend $500 on purchases within 3 months from account opening	Compare	loading Fetching your data...

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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.