Understanding Your Credit Card Number

Understanding Your Credit Card Number

March 21, 2020         Written By Tracy Farnsworth

Every credit card has a long number on the front or back. New credit cards sometimes print the card number on the back near the signature line, but you often find the number embossed on the front of the card. The other pieces of information from the front of the card are the card holder’s name, the type of credit card, and the chip. Do you know what that credit card number means? How about the other numbers you see printed on the back of a card in the top corner of the signature box? Are they random numbers, or do they serve a purpose?

If you think about the numbers you see in life, they almost always have a purpose. Your VIN on your car is a unique indicator assigned to your specific car, make, and model. No other car should have your VIN. The VIN is useful in tracking stolen cars, locating information about the car during an accident or for insurance purposes, or to keep track of warranties and recalls. Your SSN or ITIN is a specific number assigned to you for employment, banking/loans, and taxes.

Credit card numbers also have a purpose. They’re a unique number assigned to your account. It tells people about your credit card issuer, your account number, and more. People are not assigned identical numbers. If someone else is using your account, you need to notify your bank and authorities and report the fraudulent activity.

What Do the Numbers Mean?

All credit card issuers use the American National Standards Institute’s system to come up with the Major Industry Identifier (MII), which is followed by the Bank/Issuer Identification Number (BIN) and Primary Account Number (PAN).

Most credit cards are 15 or 16 digits long. Discover, Mastercard, and Visa are 16 digits, but American Express is 15 digits. There are banks that issue card numbers with 19 digits though it is not as common. At the bare minimum, the credit card number will have 13 digits, but this is not common.

The very first number is known as the MII. The MII tells you what type of card it is. These are the most common MIIs:

0: ISO/TC 68 and other industries
1 and 2: Airlines and some financial industries
3: Entertainment and travel like American Express, Diners Club, and JCB
4: Banking – Visa
5: Banking – Mastercard
6: Retailer/Store cards like Home Depot’s store card and banking (Discover)
7: Petroleum/fuel cards like the Exxon Mobil credit card
8: Healthcare and telecom
9: Not currently used but can be assigned in the future

Your credit card is always going to start with one of these MIIs. Some are far more common than others. You will not often see numbers other than 3, 4, 5, 6, and 7 in use.

How Are Credit Card Numbers Assigned?

The MII is the first digit in the card number, but what about the others? Digits 2 through 6 are BINs. These digits identify the credit card company that issued the card and to whom you make payments. Not every credit card company uses all of these digits to identify themselves. For example, Visa uses 2 through 6, but Mastercard may opt to use 2 and 3, 2 through 4, 2 through 5, or 2 through 6. American Express uses digits 3 and 4 to identify the bank and others to determine the type of currency used.

Depending on the length of your credit card, digits 7 to 18 are identifiers for your specific account or the PAN. This unique number links the card to your account with the credit card company.

The very last digit of your credit card number is known as a “check digit.” It’s a unique identifier designed to prevent invalid credit card numbers from being used. While other numbers in a card have a specific meaning, that check digit is random, which puts the chances of getting the right check digit at 1 out of 10, which is in addition to getting the other 12 to 18 digits correct.

The Importance of Intricate Credit Card Numbers

Why are card numbers so intricate? They need to be. With this system, there are a trillion possible numbers for credit cards. Without this many, it would be easier for thieves to correctly guess credit card numbers. An IBM engineer came up with this system to prevent fraud in 1954. His system, the Luhn Algorithm, is used for assigning everything from bank routing numbers and credit cards to VINs and bar codes.

A 2016 Newcastle University study found that hackers could guess a Visa number in less than 10 seconds using a Distributed Guessing Attack. This was alarming, but there are two other ways to prevent fraud. The expiration date may not be impossible to figure out, but it would take time and might flag a lot of incorrect attempts. Those incorrect attempts could be caught by the credit card company’s fraud department.

The Card Verification Value (CVV) is random and never stored anywhere. Paired with your credit card number’s check digit, it is very tough to guess all components needed to steal a credit card. You will find the CVV number on the back of most credit cards, but it might be on the front of your American Express. It is often 3 digits, but American Express uses a 4-digit code.

These measures are meant to prevent fraud, but you can take steps to keep your credit card number safe. When you use it for an online purchase, make sure you are on a trusted, secure site. Never send your credit card number, expiration, and CVV to an online seller via email. In a store, keep your hand over the card number. You never know if someone behind you has a camera app loaded and is snapping pictures of your card while you wait to pay. Don’t give credit card information using your car’s hands-free calling technology. If your speakers are loud enough or windows are down, people outside could hear every number the system or representative reads back to verify the information is correct.

Don’t leave your card on the counter or cart seat while you’re finishing bagging or gathering your order. Someone could take it, but you also might forget it on the counter. As soon as you run the card, return it to your wallet immediately and put the wallet back in your purse or pocket. Finally, consider using a payment app like Apple Pay or GPay and leave your credit card at home in your safe. Touchless payments are a secure, easy way to pay for items without ever having a card visible to others.

What Other Numbers Appear on a Credit Card?

The long number on the front or back of a credit card is the most important when you arere making purchases. The expiration date and CVV are also needed to finish many purchases if you arere not swiping the card or inserting the chip into a chip reader. There are other numbers that you may see. What do they mean?

The expiration date is useful for a company as it gives them a chance to reissue a card before yours wears out, to add new security features, or to look over your account before issuing the new card to see if you should have your APR or credit limit changed. The expiration date is clear, but some cards also have an older date. If that appears on your card, it is the date you opened the account.

At the top of the back of your credit card, you might see fine print with a name and number. That is usually the company that provided the secure credit card technology. Next to the company name is an identification number. ABCorp, IDEMIA, and Oberthur Technologies are examples of the companies found on the card. You never have to worry about this information, but it is there for your credit card company’s sake.

Turn the card over to the signature box. In addition to the CVV, you might find an additional four-digit number. That is the last four numbers of your credit card. It is there as a double-check when a card is printed.

The other numbers you see on a credit card are phone numbers used to contact the credit card company. These numbers should be self-explanatory, but they will usually offer a toll-free number and local number.

Now that you know how card numbers are developed, does it change much for you? Not really. You are still going to use your credit card in the same way you always have. You might swipe it at the register, insert the chip into the chip reader, use a payment app, or type in the credit card number when making your online purchase. It does, however, ensure you that credit card numbers are created with care to prevent fraud and abuse.

The credit card number does go a long way to keeping you safe. Are there other things you should consider when applying for a credit card? Have you considered the risk of fraud itself? If someone were to steal your credit card number, would you be held responsible? It is worth looking at credit cards with $0 liability on unauthorized purchases.

The information contained within this article was accurate as of March 21, 2020. For up-to-date information on any of the terms, cards or offers mentioned above, visit the issuer's website. Many of the offers on this article are from our affiliate partners, and LowCards.com may be compensated if you take action with any of our affiliate partners.

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tracy

About Tracy Farnsworth

Tracy Farnsworth went straight from a business track in high school to a full-time job in mortgage banking in Burlington, Vermont. After having children, she built a freelance career in content writing and took online classes as time allowed. She completed Social Media Marketing and Digital Marketing certificate programs with Ireland's online Shaw Academy and completed several courses in SEO and analytics. In her free time, she's the “mom” to a very clingy rat terrier, and the pair walk at least a mile every day. She's also a novice baker who is trying to master the art of sourdough bread.