Bank Identification Numbers

“Bank Identification Number,” or BIN code, refers to the initial sequence of four to six numbers that appears on a credit card. The number is used to identify the card’s issuing bank or other financial institution.

The BIN number ties an issuer to all the cards it issues, and to all the transactions on those cards. At the top of this page, you can use our BIN number lookup tool and use the credit card identifier system to determine the issuing bank of (almost) any payment card.

In the rest of this post, we’ll take a closer look at these bank id numbers, what they mean, and how they may change in the future.

What Is a Bank Identification Number?

First, lets answer: what is a BIN? Like most industries, the payments sector is littered with its own slate of undecipherable acronyms and confusing argot. The BIN is a perfect example. What is it? How does it differ from an IIN? And what do all those numbers mean, anyway?

The BIN (or bank identification code) is a numbering convention developed to identify which particular institution issued a given credit card or other bank card, and what type of institution it is. It’s essentially the bank’s calling card; each card-issuing bank has a unique BIN.

To start, let’s look at the full set of numbers on the front of a typical bank card. This numbering system applies to credit/charge cards, debit cards, prepaid cards, and certain electronic benefit cards. For the purposes of this article, we lump them all together under the blanket term “payment card.”

Bank Identification Numbers

In this illustration, the first six digits are traditionally called the Bank Identification Number. It’s becoming more common, however, to use the term Issuer Identification Number, or IIN. This reflects an increasing number of non-bank institutions who opt into the BIN network. However, the terms IIN and BIN can be used more or less interchangeably.

Don't forget to try the bin checker tool at the top of the page to test for yourself. 

In either case, the number can vary between four and six digits, depending on the specific institution that issued the card. While using the first six numbers is the most common, it isn’t mandatory, and even that may change soon, as we’ll discuss later.

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The Major Industry Identifier

The first digit of the card number is the Major Industry Identifier, or MII, and it possesses a certain significance on its own. The MII identifies the category or type of institution which issued the card. Visa- and MasterCard-branded cards, for example, are primarily issued by banks, and so they are classified as financial payment cards. Diner’s Club and American Express are considered travel and entertainment cards, as this was their primary function at the time they debuted.

This chart spells out the MII codes by category:

MII Digit Value Issuer Category
0 ISO/TC 68 Assignment
1 Airline cards
2 Airlines cards (and other future industry assignments)
3 Travel and Entertainment Cards
4 Banking and Financial Cards
5 Banking and Financial Cards
6 Merchandising and Financial Cards
7 Gas Cards, Other Future Industry Assignments
8 Healthcare Cards, Telecommunications, Other Future Industry Assignments
9 For Use by National Standards Bodies

To recap, when looking at the full bank card number, the first digit identifies the card issuer’s industry, while the first six digits collectively identify the specific institution which issued the card. The remainder of the 16 (or 15, in some cases) digits make up the cardholder’s account number, including one or more check digits, also called a “checksum.” A checksum represents the sum of a formula that helps determine if the credit card number is actually valid.

With the numbering combinations available, it is possible for each issuer to have about a trillion different account numbers for their cardholders.

How Bank Identification Numbers Help

The BIN/IIN provides merchants with a lot of other information besides just the issuing entity. For example, when cardholders enter card details for an online transaction, just those first few digits tell the retailer:

  • The name, address, and phone number of the bank funds will be transferred from
  • The card brand (Visa, Mastercard, American Express, etc.)
  • What type of card it is (debit, credit, prepaid, etc.)
  • What level the card is (black, platinum, business)
  • Whether the issuer is in the same country as the device used in the transaction
  • Whether the address provided by the cardholder matches the one on file

Finally, the BIN/IIN allows merchants to accept multiple forms of payment and speed up the overall processing.

Here are a few examples of the BIN format for the most widely-used card brands in the US:

Visa: 4*****

American Express (AMEX): 34**** or 37****

Diner’s Club: 36****

MasterCard: 51**** or 55****

Discover Card: 6011, 622126-622925, 644-649, 65


Your Future Bank Identification Number

As the world shifts more and more toward a digital-reality, the role of the bank identification number will likely expand. By default, this means more unique BINs will be needed. The term “BIN” itself will most likely give way to IIN eventually, as new industries enter what has traditionally been banks’ operating environment.

While there’s no shortage of account numbers right now, industry insiders think long-term. In 2016, the International Organization for Standardization (ISO) announced changes to the BIN/IIN, including expanding it from six digits to the first 8. Additionally, Mastercard introduced “account ranges” to use a single BIN across multiple products, and expanded into the little-used 2-series BIN cards. As of now, issuers and their processors are not required to move to 8-digit BIN, but they may adopt an 8-digit BIN standard if they choose.

How to Make BINs Work for You

There are additional ways that BIN, IIN and MII numbers can be used to help merchants analyze and assess their payment card transactions. More–and more accurate–information can lead to more efficient operations, but the analysis process can be quite involved. That’s why it helps to have professionals in your corner.

If you’d like more information on how to use the bank identification number to your advantage, contact Chargebacks911® today. Our payment experts have the experience and expertise to help you explore different reporting and revenue optimization techniques.