BIN (Bank Identification Number)

BIN (Bank Identification Number) is the leading string of digits on a payment card — the first six, or up to eight under the newer standard — that identifies which bank issued the card, which network runs it, and what kind of card it is. It's also called the IIN (Issuer Identification Number). The rest of the card number identifies the individual account.

What a BIN reveals

From the BIN alone, a merchant or processor can look up:

• The [issuer](/glossary/issuer) — the bank that issued the card and will authorize charges against it.
• The [card network](/glossary/card-network) — Visa, Mastercard, Amex, Discover, and so on.
• The card type and level — debit vs credit, consumer vs commercial, standard vs premium/rewards.
• The issuing country — useful for cross-border rules and fraud checks.

These attributes drive real decisions: a commercial card in the US carries different interchange than a consumer debit card, and a mismatch between the BIN's country and the buyer's stated location can raise a fraud flag.

The 8-digit expansion

Card networks moved from 6-digit to 8-digit BINs to avoid running out of ranges as card issuance grew. Systems that parse only the first six digits can misclassify newer cards, so processors and fraud tools have updated their BIN tables to read the longer prefix.

Why it matters

BIN data helps route and price a payment correctly and flag anomalies before authorization. It's also abused: in card testing attacks, fraudsters generate candidate numbers within a known BIN range and probe them against a checkout. A saved card stored via tokenization keeps the BIN visible (typically the first digits plus the last four) while hiding the full number, so merchants can still classify a stored card without holding the sensitive digits.