Validators & Calculators
Luhn checksum validator and bitmap conversion tools
Enter a card number to validate using the Luhn checksum algorithm.
Convert between hex and binary bitmap representations.
Related Tools
What is the Luhn Validator?
The Luhn Validator checks whether a credit card number or other identifier passes the Luhn algorithm (mod 10) checksum validation. It also includes a hex-to-binary bitmap calculator for ISO 8583 message bitmaps.
- Enter a card number or numeric string.
- Click Validate to check the Luhn checksum.
- The tool shows whether the number is valid and displays the check digit calculation.
What is the Luhn algorithm?
The Luhn algorithm (also called mod 10) is a checksum formula used to validate identification numbers such as credit card numbers, IMEI numbers, and national provider identifiers. It detects single-digit errors and most transpositions of adjacent digits.
Do all credit card numbers use Luhn?
Yes. All major card networks (Visa, Mastercard, Amex, Discover, JCB, UnionPay) use the Luhn algorithm to validate card numbers. The last digit is the check digit computed by the algorithm.