Luhn Algorithm Checker
Free online luhn algorithm checker that runs entirely in your browser.
How the Luhn Algorithm Checker works
The Luhn Algorithm Checker works on Card numbers (one per line) and shows the result as you type. The same input always gives the same answer — refresh the page and you will see exactly the same figure.
Formula used
Luhn Algorithm Checker is computed by the formula below, using the inputs you provide.
Inputs used: Card numbers (one per line).
Worked example
Take the default example — card numbers (one per line) of ToolFactory:
- list: BAD ToolFactory (unknown)
- okCount: 0
- total: 1
Frequently asked questions
- Is the Luhn Algorithm Checker free?
- Yes. There is no signup, no usage limit and no watermark — the checker runs entirely in your browser.
- Does the Luhn Algorithm Checker store or send my data?
- No. Every calculation happens locally in the page, so the numbers you type are never uploaded or logged.
- Does it work on a phone and offline?
- Yes — the page is a single lightweight file that adapts to any screen size. Once it has loaded it keeps working without a network connection.
- What inputs does the Luhn Algorithm Checker need?
- Card numbers (one per line). Change any of them and the result updates instantly.