Note:
Since VISA and MASTER Cards are the most widely available cards, I have used them for my research. But the results hold true for all card types.
Identifying Card Issuer Type
The first digit in a card represents the Major Industry Identifier and is known as MII digit. It represents the category of entity which issued your credit card. There are following types of issuers:
MII Digit |
Issuer Type |
| 0 | ISO/TC 68 and other industry assignments |
| 1 | Airlines |
| 2 | Airlines and other industry assignments |
| 3 | Travel and entertainment (such as American Express and Diners Club) |
| 4 | Banking and financial (Visa) |
| 5 | Banking and financial (MasterCard) |
| 6 | Merchandizing and banking (Discover) |
| 7 | Petroleum |
| 8 | Telecommunications and other industry assignments |
| 9 | National assignment |
You can understand this better by taking out your card and seeing the first digit. If you own a petroleum card (such as those issued by Exxon Mobil or BP) then your card number will start with 7. If you own a debit/credit card issued by a bank then it will start with 4 or 5 (depending on whether it is a Visa card or Master card).
You can understand this better by taking out your card and seeing the first digit. If you own a petroleum card (such as those issued by Exxon Mobil or BP) then your card number will start with 7. If you own a debit/credit card issued by a bank then it will start with 4 or 5 (depending on whether it is a Visa card or Master card).
Identifying Card Issuer
|
Issuer |
IIN |
|
American Express |
34xxxx, 37xxxx |
|
VISA |
4xxxxx |
|
Master Card |
51xxxx-55xxxx |
So if you have a card that starts with 51 that means it is a Master Card.
Note:
During my study I observed that Maestro card starts with 50 and 62. If you know something about Maestro cards, please share it through your comments.
Mathematically speaking, there can be 10 raised to power 6 (since 6 digits are used to identify an issuer), i.e. 1 million unique card issuers !!
Finding Account Number
Starting from the seventh digit to second last digit, i.e., 7th to n-1 digit in a card represents the account number. I noticed that this account number is not the same as your bank account number. For cards issued by ICICI (whether VISA or MASTER Cards), only first five digits of the card number and the account number matched, while there was no such similarity for cards issued by HDFC bank.
Conclusion:
7th to n-1 digit in the card represents the account number. This account number is not the account number of your bank but the account number generated by the Card Issuer (such as VISA or Master Card) to uniquely identify you.
A card can have a maximum of 19 digits. So the account number can be a maximum of 12 digit number. That means each issuer can issue a maximum of 10 raised to the power 12, i.e., 1 trillion cards !!
Check Digit
The last digit on the card is known as the check digit and it determines whether it is a valid card or not.
