What does this tool do?
Luhn Generator computes the check digit of a number using the mod-10 (Luhn) algorithm and validates existing numbers. Enter a digit string without its check digit to get the completed, valid number, or paste a number to see whether it passes Luhn. It is useful for developers, anyone preparing test data, and people learning how validation logic works.
How to use it
- Choose the required options or length.
- Generate the secure result.
- Copy and store the result safely.
How the Luhn algorithm works
Starting from the right, Luhn doubles every second digit; if a result exceeds 9, you subtract 9. All digits are summed, and the check digit appended at the end is whatever makes the total divisible by 10. To validate, the algorithm checks that the sum of the whole string, including the check digit, is divisible by 10. This simple checksum catches common typos such as single-digit errors and most adjacent-digit transpositions.
Where it is used
Luhn serves as a first validation layer in credit card numbers like Visa and Mastercard, in the IMEI serial numbers of phones, and in some SIM (ICCID) and ID numbers. Important: Luhn is only a format checksum; it never proves a number is real, active, or linked to any account. This tool is meant for testing and learning, and it runs entirely in your browser without sending any sensitive input to a server.
Frequently asked questions
Can I create a valid credit card number with this tool?
You can only produce digit strings that pass the Luhn checksum; they are format-valid but are not real, usable cards. The tool is suited for software test data, not for fraud.
What exactly is a check digit?
A check digit is a single digit appended to the end of a number. It is derived from the other digits by the Luhn formula and makes the string's total a multiple of 10, so simple typing mistakes are caught instantly.
Do spaces and dashes in my number cause problems?
No. The tool automatically strips all non-digit characters such as spaces and dashes before validating or calculating, so you can paste a card in its grouped, formatted form.
Is Luhn Check Digit Generator free?
Yes. Luhn Check Digit Generator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Luhn Check Digit Generator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.