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Card Number Validator (Luhn Check)

Check whether a card number is well-formed and which network it belongs to.

  • Free
  • No sign-up
  • Nothing is sent or stored

Use test numbers. Validation happens in your browser and nothing is sent or stored.

Result

✓ Passes the Luhn check
4111 1111 1111 1111
Card network
Visa
Length
16 digits
Issuer identification (first 6)
411111
Check digit
1
Passing the Luhn check only means the number is well-formed — not that the card exists, is active or has funds.

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved.

How to use the Card Number Validator (Luhn)

  1. Enter a card number (test numbers like 4111 1111 1111 1111 work).
  2. Read whether it passes the Luhn check.
  3. See the detected card network and length.

What does this tool do?

Card numbers end in a check digit calculated with the Luhn algorithm, which catches most single-digit typos and swapped digits. Developers use this check to validate input before sending it to a payment processor.

The first digits identify the network: 4 for Visa, 51–55 or 2221–2720 for Mastercard, 34 or 37 for American Express.

Why use it?

  • Luhn validation.
  • Network detection.
  • Runs only in your browser.

Accuracy and limits

  • Passing the check doesn't mean a card is real or active. Use test numbers — never share real card details with websites you don't trust.

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed by the M2Toolkit team.

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