Card BIN Format Checker

About this calculator

The first 6–8 digits of a payment card number — its BIN/IIN (Bank/Issuer Identification Number) — encode the card network and issuing bank: Visa numbers start with 4, Mastercard with 51–55 or 2221–2720, American Express with 34 or 37, Discover with 6011 or 65, and so on, each network also fixing an expected total card length. The final digit is a check digit computed with the Luhn algorithm, which doubles every second digit from the right, sums the digits, and requires the total to be a multiple of 10.

This checker reads the BIN prefix to identify the network, confirms the number length matches that network's standard, and runs the Luhn check — all without validating that the card is real, active, or has any funds. Payment developers testing checkout flows, and fraud-review or support staff use it to catch obviously malformed or mistyped card numbers before they ever reach a payment processor.