Bank Identification Number (BIN) Definition
A Bank Identification Number (BIN) — also known as an Issuer Identification Number (IIN) — is the first 6 to 8 digits printed on a payment card. These digits serve as a unique identifier for the financial institution that issued the card, the card network it belongs to, and the type of card product.
Every credit card, debit card, prepaid card, and gift card issued worldwide carries a BIN. When a transaction is initiated, payment processors read the BIN first to route the transaction to the correct card network and issuing bank.
How Does a BIN Number Work?
When you swipe, tap, or enter your card number online, the payment terminal or gateway reads the BIN digits first. Here's the step-by-step flow:
- BIN Identification — The payment system extracts the first 6–8 digits to identify the card issuer and network.
- Network Routing — The transaction is routed to the appropriate card network (Visa, Mastercard, Amex, etc.).
- Issuer Authorization — The card network forwards the request to the issuing bank for approval.
- Response — The issuing bank approves or declines the transaction and sends the response back through the network.
What Is the Structure of a Card Number?
| Digits | Name | Purpose |
|---|---|---|
| 1–6 (or 1–8) | BIN / IIN | Identifies the issuer, network, and card type |
| 7–15 | Account Number | Unique identifier for the individual cardholder |
| 16 | Check Digit | Luhn algorithm validation digit |
The first digit also indicates the Major Industry Identifier (MII):
| First Digit | Card Network / Industry |
|---|---|
| 1, 2 | Airlines |
| 3 | American Express, Diners Club, JCB |
| 4 | Visa |
| 5 | Mastercard |
| 6 | Discover, UnionPay |
| 7 | Petroleum industry |
| 8 | Healthcare, telecommunications |
| 9 | National assignment |
What Information Does a BIN Reveal?
Using our free BIN checker tool, you can discover:
- Card Network / Scheme — Visa, Mastercard, American Express, Discover, JCB, UnionPay, etc.
- Issuing Bank — The financial institution that issued the card (e.g., Chase, HSBC, Barclays).
- Card Type / Funding — Whether the card is a credit, debit, or prepaid card.
- Card Product / Level — Classic, Gold, Platinum, Signature, Infinite, Business, Corporate, etc.
- Country of Issuance — The country where the card was issued.
- Currency — The default currency associated with the card account.
- Card Segment — Consumer, commercial, or corporate classification.
BIN vs IIN — What's the Difference?
There is no functional difference. Both refer to the same leading digits. "BIN" was historically used when the digits were always 6 digits long. In 2017, the ISO updated the standard to use "IIN" as the official term. Despite this, "BIN" remains dominant in industry vocabulary.
Why Are BIN Numbers Important?
1. Fraud Prevention
BIN data helps detect fraud by identifying mismatches — e.g., a card issued in Germany being used with a U.S. billing address. Bank card lookup tools are widely used by fraud teams.
2. Payment Routing
Payment processors use BINs to route transactions to the correct acquiring network.
3. Interchange Optimization
Different card types carry different interchange rates. Credit card BIN lookup helps merchants understand transaction costs.
4. Customer Experience
Auto-detecting the card network from the BIN allows merchants to display the correct card logo in real-time during checkout.
5. Regulatory Compliance
Some jurisdictions require different processing rules based on whether a card is domestic or foreign.
How to Look Up a BIN Number
Use our free BIN checker — enter the first 6–8 digits and click Lookup. Or use our specialized tools:
- Visa BIN Checker — for cards starting with 4
- Mastercard BIN Checker — for cards starting with 5 or 2
- American Express BIN Checker — for cards starting with 34 or 37
6-Digit vs 8-Digit BIN Numbers
Until 2022, all BINs were 6 digits. The ISO/IEC 7812 standard was updated to extend BINs to 8 digits, providing up to 100 million possible combinations. Our card number lookup tool supports both formats.