Luhn Validation Ruby Gem



Luhn_Validation is a ruby gem implementing the Luhn (Modulus 10) algorithm commonly used for credit card validation.


This software can only be used to check if a given number passes the Luhn algorithm. In cannot determine if a given number belongs to a credit card that is legitimate, in service or in any way valid as it does not interact with any financial institutions.

Refer to the License for further details.


gem install luhn_validation


Require the gem:

require 'luhn_validation'

Instantiate a validation object:

luhn_val =

Validate the credit card number. Note that basic string sanitising is performed, acceptable formats include:

  • Alpha character separated strings such as hyphens (4444-3333-2222-1111) or whitespace (4444 3333 2222 1111) etc.

valid? returns true if the number passes luhn validation, false otherwise.


You can also access the validation object’s more recently processed number via the cc_dirty and cc_clean attributes.

luhn_val.cc_dirty # => '4444-3333-2222-1111'
luhn_val.cc_clean # => 4444333322221111


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