Check a number with the Luhn algorithm

Before an entry, import or submission, this helps teams and individuals catch a malformed value early. Check a number with the Luhn algorithm.

Check a number with the Luhn algorithm. The result appears instantly in your browser, ready to copy, with no account, upload or storage involved.

How to use

Enter the number you want to check in the input field, removing spaces or dashes if possible.
Run the verification with the main button to apply the Luhn algorithm.
Read the result shown immediately to see whether the checksum matches.
If needed, clear the field to test another number or import a text file.

Example

Using the provided example, the number 49927398716 is checked by the tool. Look at the result to see whether the Luhn checksum is accepted; this helps you understand the behaviour before testing your own identifiers.

Input

49927398716

Limits and formats

It only checks the Luhn checksum, not whether the number exists or belongs to anyone.
A number can pass Luhn and still be invalid for the system that issued it.
Spaces, dashes or letters may need to be removed before checking a real-world value.
For important decisions, confirm the result with the official source.

Where processing happens

The check runs entirely in your browser, so the number you type stays on your device and is not sent anywhere. No account is required, and nothing is stored after you leave the page.

Frequently asked questions

What kinds of numbers can I test?

The tool applies the Luhn algorithm to the string you enter. It is useful for identifiers that use a Luhn checksum, such as some card numbers or administrative references, as long as the characters fit the expected format.

What does a positive result mean?

A positive result means the checksum matches the Luhn algorithm. It does not prove that the number exists, is active or belongs to a person, so you should still verify it with the relevant source.

Can I import a file instead of typing?

Yes, you can import a text file or formats such as CSV, JSON, Markdown, XML or YAML. The imported content is processed in your browser, and you can then run the verification just as with manual input.