Enter a credit card or IMEI number, and the tool validates it against the Luhn algorithm and computes the correct check digit.
A simple checksum (mod 10) formula that validates identification numbers such as credit cards, IMEI numbers, and some national IDs. It catches most single-digit typos and adjacent transpositions.
No — Luhn only verifies the check digit is consistent. It does not mean the card exists or is active. No data is sent anywhere; validation runs entirely in your browser.
Enter the number without its last digit and the tool appends the digit that makes the full number pass the Luhn check.