What Is a BIN Number? BIN vs IIN & ISO/IEC 7812 Explained
Explore how the first 6 to 8 digits of a credit card identify the card brand, issuing institution, and industry classification under international payment standards.
Looking to inspect a specific 6 or 8-digit BIN prefix?
Use our safe BIN checker to identify card scheme, MII classification, and length specifications without exposing private numbers.
Synthetic cards are generated strictly for software engineering, user-interface validation, and automated QA tests. They are not issued by financial institutions, carry no credit balance, and are not intended or verified for live payment authorization.
What Is a BIN / IIN Number?
BIN (Bank Identification Number) is a commonly used industry term for the Issuer Identification Number (IIN). Modern ISO/IEC 7812 implementations support 8-digit IINs, while 6-digit BIN/IIN terminology remains common in legacy systems and industry usage. These opening digits identify the payment network and issuing organization range responsible for the card program.
When a consumer types a card number into an e-commerce checkout form, the merchant's payment software inspects these opening digits to determine:
- The Card Scheme / Network: (Visa, Mastercard, American Express, Discover, JCB, or UnionPay).
- Appropriate Form Formatting: (e.g., 4-4-4-4 spacing for 16-digit cards versus 4-6-5 spacing for 15-digit Amex cards).
- Routing & Processing Rules: (Routing transactions to correct payment switches and identifying debit vs. credit interchange tiers).
Anatomy of a Credit Card Number
Under ISO/IEC 7812, every Primary Account Number (PAN) consists of three distinct mathematical segments:
Issuer Identification Number (IIN)
The first digit is the Major Industry Identifier (MII). Together with subsequent digits, it identifies the network brand and the licensed issuer institution range.
Individual Account Identifier
Assigned by the card issuer to uniquely identify the customer's account or digital token within their private portfolio.
Luhn Mod 10 Check Digit
Calculated using the Luhn algorithm to protect against manual input mistypes and transposition errors.
Major Industry Identifier (MII) Classification
The very first digit of an IIN is the Major Industry Identifier (MII). It classifies the broad commercial sector of the card-issuing entity under ISO/IEC 7812. The MII categorizes the industry type rather than identifying an individual issuing bank on its own:
| MII Digit | Primary Industry Sector | Prominent Real-World Examples |
|---|---|---|
| 0 | ISO/TC 68 and specialized industry assignments | System identification & specialized financial carriers |
| 1 | Airlines | Airline frequent flyer credit accounts |
| 2 | Airlines, Financial & other assignments | Mastercard 2-series BINs (2221–2720) |
| 3 | Travel and Entertainment | American Express (34, 37), Diners Club, JCB (3528–3589) |
| 4 | Banking and Financial | Visa (all 4xxxx cards worldwide) |
| 5 | Banking and Financial | Mastercard 5-series (51–55) |
| 6 | Merchandising and Banking | Discover (6011, 65, 644–649), China UnionPay (62), Maestro |
| 7 | Petroleum | Oil company fleet and fuel charge cards |
| 8 | Healthcare and Telecommunications | Health insurance cards, telecom fleet accounts |
| 9 | National Assignment Bodies | Government programs & national clearing systems |
The Modern 8-Digit IIN Migration (ISO/IEC 7812-1:2017)
Historically, a BIN comprised exactly 6 digits. Growth in the number of issuers and increasing demand for issuer identifiers placed pressure on the available 6-digit IIN space. ISO therefore expanded the IIN from 6 to 8 digits in the updated ISO/IEC 7812-1:2017 standard, while keeping the total PAN length unchanged. Consequently, 6 digits are no longer universally sufficient for modern issuer identification across all global payment networks.
Visa and Mastercard introduced major 8-digit BIN/IIN support requirements in April 2022. Existing 6-digit identifiers did not universally disappear, so payment systems may need to support both legacy 6-digit and modern 8-digit values.
Impact on Software Testing:
Software that relies on BIN/IIN identification should support both 6-digit legacy identifiers and applicable 8-digit IINs. Network detection and issuer-range identification should remain separate validation concerns. In our Safe BIN Checker, inputs accept any 6 to 8 digit sequence for seamless testing of both legacy and modern 8-digit IIN ranges.
Frequently Asked Questions
What is the difference between a BIN and an IIN? ↓
BIN (Bank Identification Number) is a commonly used industry term for the Issuer Identification Number (IIN). Modern ISO/IEC 7812 implementations support 8-digit IINs, while 6-digit BIN/IIN terminology remains common in legacy systems and industry usage. Formally, the IIN designation acknowledges that modern card issuers encompass non-bank fintechs, credit unions, airlines, and digital platforms as well as traditional banks.
Why did ISO/IEC 7812 expand IIN length from 6 to 8 digits? ↓
Growth in the number of issuers and increasing demand for issuer identifiers placed pressure on the available 6-digit IIN space. ISO therefore expanded the IIN from 6 to 8 digits in ISO/IEC 7812-1:2017. Visa and Mastercard introduced major 8-digit BIN/IIN support requirements in April 2022, while legacy 6-digit identifiers continue to be supported alongside modern 8-digit values.
Does knowing a BIN or IIN prove that a card account exists? ↓
No. A BIN/IIN identifies numbering and issuer/network ranges, not whether a specific account exists, is active, has funds, or is authorized for payment. Prefix analysis inspects public card structure and does not query private issuing-bank databases or process transaction authorizations.
Does using the BIN Checker submit card data to a server? ↓
The BIN/IIN checker analyzes supported prefix patterns locally in the browser and does not intentionally submit the entered prefix to our application server. Only test prefixes should be used.
Related Payment Testing Tools & Resources
Safe BIN Checker
Inspect the 6–8 digit BIN/IIN prefix and identify supported card-network patterns.
Credit Card Validator
Validate card length, network prefix schemes, and Modulo 10 Luhn checksums locally.
Card Number Generator
Create synthetic test cards using supported card-network prefix and PAN-length rules.