What does 'passes the Luhn checksum' actually confirm?

It confirms the number is internally consistent with the Luhn (mod 10) algorithm used by all major card issuers, catching typos and randomly guessed numbers. It does not confirm the card is actually issued, active, or has available funds.

Why does it identify a network like Visa or Mastercard?

Card networks use distinct leading-digit (IIN/BIN) ranges, for example Visa numbers start with 4, and Mastercard numbers start with 51-55 or 2221-2720. The prefix alone is usually enough to identify the likely network.

Credit Card Number Validator

Check if a card number passes the Luhn checksum and identify its network.

How this is calculated

Luhn algorithm: double every second digit from the right, sum all digits, valid if total is a multiple of 10

Assumptions used in this calculation

Format check only: This only checks the Luhn checksum and prefix, it does not verify the card is real, active, or has funds.

About this calculator

The credit card validator checks whether a card number passes the Luhn (mod 10) checksum algorithm and identifies its likely card network from the prefix.

Worked example

A sample Visa test number

Result: Valid, Visa

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About this calculator

Frequently asked questions

What does 'passes the Luhn checksum' actually confirm?

Why does it identify a network like Visa or Mastercard?

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