A Bank Identification Number (BIN) is a series of 4 to 6 numbers on a credit or debit card that can be used to identify which bank or institution issued the card.
BIN numbers are standardized and may also be used on gift cards, pre-paid cards, and other types of payment cards.
How Bank Identification Numbers Work
The first digit of the card identifies the industry of the institution that issued the card (financial, airlines, or travel and entertainment). The following digits specify the issuing institution, the issuing country, and the type of card.
For example, BINs with a prefix of 4 are visa cards, while 51-55 are issued by Mastercard.
Online merchants can use this information to help validate card transactions and to flag potentially fraudulent transactions.
After the customer has entered the first 4-6 numbers of their payment card, the checkout can detect:
- The type of card being used (credit, debit, or other)
- The card brand (Visa, Mastercard, American Express, etc.)
- The level of the card (standard, platinum, corporate, etc.)
- The country of the issuing bank for the card
The payment processor can use this information to assess transactions in several ways:
- Check if the customer is in the same country as the issuing bank
- Identifying the issuing bank along with its address and telephone number
- Identifying if the account associated with the card is valid
- Verifying the address information supplied by the customer
- Identifying pre-paid cards, which may not be suitable for paying subscriptions or other recurring transactions
The BIN identifies which institution to request payment authorization from. If the card is invalid or there are insufficient funds in the account, the payment will be declined.
Major Industry Identifier (MII) Codes
The first digit of the card number identifies the industry of the institution that issued the card as follows:
- 0 – ISO/TC 68 assignment
- 1 & 2 – Airline cards
- 3 – Travel & entertainment cards (Diner’s club and American Express come under this category as they were originally issued for this purpose.)
- 4 & 5 – Banking & financial cards
- 6 – Merchandising & financial cards
- 7 – Gas cards & other future assignments
- 8 – Healthcare & telecommunications cards & other future assignments
- 9 – National standards bodies
Understanding The Rest of the Card Number
After the MII code, the following 3-5 numbers identify the institution that issued the card.
Following the BIN is the customer account number with the final digit used as a checksum to determine if the card number is valid.