What Is a BIN Number and How to Read It
Published: October 20, 2026 · By Marcus Hale, CC Market Analyst
A BIN (Bank Identification Number) is the first six digits of a payment card. Those six digits encode the issuing bank, the card brand, the card level and the country of issue. The BIN is also called the IIN (Issuer Identification Number).
How to read a BIN
Take the first six digits of a card number and run them through a BIN lookup tool. The tool returns the issuer name, brand, card level and country. Only the first six digits are needed - never paste a full card number into a third-party tool.
| Digits | Meaning |
|---|---|
| 1-2 | Brand indicator (4=Visa, 5=Mastercard, 3=AMEX, 6=Discover) |
| 3-6 | Issuer-specific (bank and level) |
| 7-16/19 | Account number (not part of BIN) |
BIN changes over time
Issuers reorganise portfolios, so BIN assignments change. Treat BIN results as a strong hint and verify against a current database for production use.
Try the free BIN lookup tool
Use the BIN Lookup tool to identify a prefix. Related: BIN Lookup Guide, BIN Range Lookup.
Why BINs matter for developers
When building payment forms, checkout flows or fraud tools, the BIN is the first useful signal. It tells you the brand, the likely country and the card level before any authorization request is made. That lets you route transactions to the right processor, apply brand-specific length rules and reject obviously malformed numbers early. It also lets you localize the checkout experience, for example by showing the right billing-address fields for the issuer country.
Common mistakes when reading a BIN
The most common mistake is assuming a BIN never changes. Issuers reorganise portfolios, banks merge and card products are retired. A prefix that mapped to one bank last year can map to another this year. A second mistake is treating a BIN as proof that a card is valid. The BIN only describes the prefix; the Luhn checksum describes the number structure; neither proves the card exists or has funds.
How to verify a BIN in practice
Use a lookup tool to get the issuer, brand and country, then verify the full number with a Luhn check and the brand-specific length rule. For production systems, keep your own BIN table updated from a reliable provider and log the prefix alongside every transaction so you can audit mappings later.