What are the details of a magStripe (on credit cards) read by ATMs to verify the card?


I'm a developer, interested in developing a mobile app related to ATMs which would have virtual credit cards. I've been trying to find a way how card details are validated by ATMs, hence needed to know what are the details of a magnetic stripe that the ATM reads to validate the card.
In the below link, I found that the POS terminal checks the record of the magnetic stripe for Merchant ID, Valid card number, Expiration date, Credit card limit and Card usage to vaidate the card >> http://money.howstuffworks.com/personal-finance/debt-management/magnetic-stripe-credit-card1.htm Could anyone please confirm if the ATM too checks only for the above details i found in the link? Else, what are the actual details of a magnetic-stripe of the credit-card that the ATM reads for validation?

Credit Cards Bank Validation

asked Sep 6 '13 at 00:36
101 points
  • This question is off-topic because it is not about startups. – Zuly Gonzalez 8 years ago

1 Answer


Either you did not read the details of your link thouroughly, or you don't understand what they mean. The magnetic stripe on a credit card or ATM card contains a limited amount of data. You can buy credit card readers for less than $50 and run your cards through to see what comes out. It is basically what is printed on the card, minus the security code.

The ATM does not validate anything. The ATM simply takes this information, along with a manually entered PIN number, and sends that information on to a merchant gateway. The merchant gateway routes the information to bank computers for that particular card. Algorithms at that computer determine whether or not the transaction should be accepted or denied, depending on the credit card holder's credit status, the location of the transaction, and special circumstances. So, for example, my ATM card will not normally work in China, but by calling my bank I can activate the ATM card in China for a specific period of time, and for specific maximum amounts.

The algorithms for validating a purchase vary by bank.

answered Sep 6 '13 at 02:30
Gary E
12,510 points
  • Thank you for the reply. It's pretty clear. Unfortunately, I'm in bit of a rush and shipping a magStripe reader would take a while. But I only need to know what the details are that an ATM reads of a Credit card during transactions. According to what I found in the link I posted, POS terminal reads the details : "Merchant ID, Valid card number, Expiration date, Credit card limit and Card usage" of a card. Need to clarify if it's the same at an ATM. – Hasitha 8 years ago
  • I don't know what country you are in, but the US doesn't even really have ATM cards anymore. We have credit and debit cards and both give the same details. Card holder name, card number, and expiration date. A "credit card limit" would be absolutely useless. Your limit is defined by the current status of your account and that can never be on your card (unless you have some sort of active data storage on the card). – Gary E 8 years ago

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Credit Cards Bank Validation