Credit Card & IBAN Validator

The Luhn algorithm (mod 10, ISO/IEC 7812) protects payment card numbers against typing mistakes. Starting from the rightmost digit (the check digit) and moving left, every second digit is doubled; if doubling gives a two-digit number, its digits are added (the same as subtracting 9). The number is valid when the total of all digits is a multiple of 10. Luhn catches every single-digit error and most swaps of adjacent digits, which is why checkout forms run it before sending anything to the payment provider.

The first digits of a card number form the IIN/BIN (Issuer Identification Number), which identifies the network and the issuing bank. Visa numbers start with 4, Mastercard with 51–55 or 2221–2720, American Express with 34 or 37, and so on (see the reference table below). Since 2022 the industry has been moving from 6-digit to 8-digit BINs, so treat brand detection from prefixes as a helpful hint, not an authoritative lookup. A number that passes Luhn and matches a brand can still be cancelled, expired or simply made up.

IBAN (International Bank Account Number, ISO 13616) is used in Europe, the Middle East and parts of Africa and the Americas. It consists of a two-letter country code, two check digits and a country-specific BBAN (Basic Bank Account Number) with a fixed length per country. To validate it, move the first four characters to the end, replace each letter with two digits (A = 10 … Z = 35) and compute the remainder modulo 97 of the resulting large number: a correct IBAN always leaves a remainder of 1 (ISO 7064 MOD 97-10). This detects all single-character errors and nearly all transpositions.

Use this page to test form validation, debug payment integrations with sandbox numbers, or double-check an IBAN before a transfer. Never paste real card data into a website, including this one; everything here runs locally, but test numbers are all you need. To redact card numbers and IBANs from logs before sharing them, use the secrets & PII scrubber. For realistic fake data sets use the mock data generator, and build validation patterns with the regex tester.