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Test Credit Card Numbers With Luhn Credit Card Validation

Published 7/11/08 (Modified 6/17/11)
By MoneyBlueBook

What Do the Credit Card Numbers Mean, and How Are Valid Credit Card Accounts Generated?

Have you ever wondered how credit card companies generate all those account numbers that appear on the face of the credit cards you carry around in your wallet? At first glance the numbers, while neatly arranged, appear to be completely random. But would it surprise you to know that there is indeed meaning and actual mathematical methodology to the way the numbers are sequenced? The process of generating real credit card numbers and validating them based on a proven mathematical formula is not only intriguing on an intellectual level and a hacker's dream, the carefully calculated way the numbers are ordered is actually quite beautiful and elegant when you come to understand how it works.

Before I get down to explaining the anatomy of credit card numbers and discussing how credit card numbers are generated, I think it's prudent to remind everyone the intent of this article. The goal of this blog post is not to encourage or get people thinking about how to go out and create fake credit card numbers on their own for improper means. The purpose is to shed some light on the science behind the mathematical sequencing technology of valid credit card numbers and offer some insight into something that many of us frequently see and use everyday, but oftentimes don't pay much attention to.

Please take in the information provided for purely academic and entertainment reasons. I'm not trying to encourage anyone to create fake credit card numbers and get themselves in trouble with the law. For anyone even thinking about engaging in fake credit card number hacking, keep this in mind - using mathematically generated credit card numbers to purchase products over the Internet or in real life is not only unethical and highly illegal, it's also not yet technologically possible (yet), based on the sheer probability of long shot odds of 1 in trillions. After reading everything I'm about to say carefully, you'll also realize that there is no realistic way to generate actual working credit card numbers that could be used for anything but entertainment reasons. The math and science behind generating authentic credit card numbers are only good for validation purposes and not sufficient for creating workable numbers as several highly encrypted numerical components are still needed. So, with that obligatory disclaimer out of the way, here is a short guide on how anyone can generate and verify the authenticity of any credit card number.

Basic Background About Credit Card Numbers and How They Work

Rather than ask you to take out a credit card out of your wallet to examine it, I've provided a picture of a prototypical card - in this case, it's a Visa credit card. While different card types offer different lengths of numerical digits, most major credit card issuers popular in the United States have 16 primary numbers on the front face of the card. Visa, MasterCard, and Discover cards all have 16 digits. American Express is the only major credit card issuer in the U.S. with one less number - at 15 digits. Regardless of the length of numbers, their numerical sequencing is still guided by the same Luhn validation formula, the mathematical check sum equation that makes all valid credit card numbers error free.

As you can see from the picture of the Visa card above, the very first 6 credit card number sequence is known as the issuer identification number (IIN) or bank identification number (BIN). These first 6 numerical digits denote the credit card network and the banking institution the card is a member of. The issuer identifier number also incorporates the card type's special identifying numerical prefix.

  • All typical 16 digit Visa account credit card numbers start with a prefix of 4.
  • All 16 digit MasterCard account numbers start with a prefix of 5.
  • All 16 digit Discover account numbers start with a prefix of 6011.
  • All 15 digit American Express credit card numbers start with a prefix of 37.

There is less randomization during this initial set of 6 digits as the numbers are determined purely by the card issuing source. Validation systems that want to go the extra mile in verifying authenticity oftentimes scan this first numerical sequence to match the known bank and issuing location of the card with the provided customer billing address for further validation accuracy.

The lone digit at the very right end of the complete 15 or 16 digit credit card number sequence is known as the "check digit", which often is the final number that is computer generated to satisfy the mathematical formulations of the Luhn check sum process. Meanwhile, in between the first 6 digits and the last single check digit is the actual personalized account number - the 8 or 9 digit sequence given by the card issuer. For more basic background information about credit card numbers, check out this credit card features brochure for more useful knowledge about the embossed and printed information found on your typical plastic credit card.

What's The Secret Behind The Luhn Algorithm, Also Known As The "Modulus 10" Or "Mod-10" Formula?

The Luhn Algorithm is the check sum formula used by payment verification systems and mathematicians to verify the sequential integrity of real credit card numbers. It's used to help bring order to seemingly random numbers and used to prevent erroneous credit card numbers from being cleared for use. The Luhn Algorithm is not used for straight credit card number generation from scratch, but rather utilized as a simple computational way to distinguish valid credit card numbers from random collections of numbers put together. The validation formula also works with most debit cards as well.

The Luhn formula was created and filed as a patent (now freely in the public domain) in 1954 by Hans Peter Luhn of IBM to detect numerical errors found in pre-existing and newly generated identification numbers. Since then, it's primary use has been in the area of check sum validation, made popular with its use to verify the validity of important sequences such as credit card numbers. Currently, almost all credit card numbers issued today are generated and verified using the Luhn Algorithm or Modulus, Mod-10 Formula. Needless to say, if you come upon some existing credit card numbers that fail the Luhn algorithm when put to the test, it is safe to assume that they are not valid or genuine numbers.

The one thing to keep in mind is that validity in terms of passing the Luhn test only means that it is mathematically valid for computational compliance purposes. It does not guarantee that the credit card number sequence is indeed a working number that is backed up with a valid credit card account on the card issuer's end. It is not unremarkable for one to artificially generate a mathematically valid credit card number that passes the Luhn validation check, but still ultimately fails as a fake credit card number with no actual substance. The Luhn algorithm only validates the 15-16 digit credit card number and not the other critical components of a genuine working credit card account such as the expiration date and the commonly used Card Verification Value (CVV) and Card Verification Code (CVC) numbers (used to prove physical possession of the debit or credit card).

The Nerdy Process Of Applying The Luhn Algorithm To The Creation and Validation Of Credit Card Number Sequences

For those who hate math or get scared when they encounter a bunch of scary looking mathematical formulas and numerically inspired descriptions, you are not alone. I personally hate math as an academic subject and was rather terrible at it back in high school and college, but if you like visual, thinking puzzles like Sudoku, you'll like working with the Luhn Algorithm. It's pretty clever and remarkably well put together. It's also pretty easy to explain.

  1. First, you'll need to lay out all 15 or 16 numerical digits of the credit or debit card number. The Luhn Algorithm always starts from right to left, beginning with the rightmost digit on the credit card face (the check digit). Starting with the check digit and moving left, double the value of every alternate digit. Non-doubled digits will remain the same. Remember that the check digit is never doubled. For example, if the credit card is a 16 digit Visa card, the check digit would be the rightmost 16th digit. Thus you would double the value of the 15th, 13th, 11th, 9th digits, and so on until all odd digits have been doubled. The even digits would be left the same.
  2. For any digit that becomes a two digit number of 10 or more when doubled, add the two digits together. For example, the digit 5 when doubled will become 10, which turns into a 1 (when 1 and 0 are added together). Likewise, the digit 9 when doubled will become 18, which becomes 9 (as 1 and 8 are added together). Obviously, 0 when doubled will remain 0.
  3. Now, lay out the new sequence of numbers. The new doubled digits will replace the old digits. Non-doubled digits will remain the same. Thus, you should be able to come up with a new sequence of 15 or 16 numerical digits depending on card type.
  4. Add up the new sequence of numbers together to get a sum total. If the combined tally is perfectly divisible by ten (ends in 0, like 60 for example), then the account number is mathematically valid according to the Luhn formula. If not, the credit card number provided is not valid and thus fake or improperly generated.

An Example Of the Luhn Validation Technique In Action - Using Homemade Graphics


For the visual types like myself, let's use the American Express credit card on the right to better demonstrate the doubling and addition mathematics of the Luhn Algorithm. Follow the numbers and you'll realize that it's not as difficult as it may first appear. It's actually very easy once you get the hang of it. You won't look at credit card numbers the same way ever again after you get a good grip of it - I assure you. You'll find yourself testing credit card numbers for fun!

Ignoring the obvious Amex logo on the card, right of the bat it's clear the account number is that of an American Express number - denoted by the numerical prefix - "37". Now let's crunch the numbers through the Luhn Algorithm using the following displayed Amex credit card number: 3759-876543-21001. It doesn't matter if the credit card number sequence has 15 numbers like the American Express or 16 numbers like Visa, MasterCard, or Discover, the Luhn validation check should be able to verify whether this card number is a mathematically authentic credit card number regardless. Follow the Luhn steps from #1 to #4 below, starting with the rightmost check digit.

In this case, the total calculated sum was 57, which is not divisible by 10 (the added up sum does not end with zero). Thus the number fails the Luhn Algorithm validation check. According to the Luhn test, this particular Amex credit card number is completely bogus and fake. The numbers were likely randomly slapped together. To make this particular set of numbers Luhn compliant and error free, all we would have to do is change the all important "check digit" number from 1 to a 4, which would result in a total sum of 60, thereby becoming Luhn compliant.

If you want to test this mathematical theory out in real life, I recommend pulling out your own credit cards and spending a few seconds to run a quick Luhn screening on them just for your own amusement and education. Pretty neat isn't it? If you want another credit card number to test on, try using the credit card number that is displayed on the cartoon "VIZA Card" [sic] that Bart Simpson is holding up in the graphic at the top right of this article - the card is in the name of "Rod Flanders", and the credit card number is: 8525-4941-2525-4158. Tip: Just by looking at the prefix numbers you probably should already be able to tell that the account number's completely random and fake.

Use The Luhn Formula To Validate Existing Accounts But Don't Attempt To Create and Use Fake Credit Card Numbers

Now with this new found knowledge, keep in mind you still won't be able to randomly generate genuine workable credit card numbers. The Luhn theory only allows you to generate mathematically compliant credit card test numbers, not hack workable ones. Besides, without valid expiration dates, and valid CVV2, CVC2, or CID numbers (the special security codes printed on the back or front of credit cards as additional authentication measures), you still wouldn't be able to legitimately use your self generated numbers to run credit transactions anyway.

Cracking and hacking the security codes found on credit cards is currently impossible. To calculate a workable 3 digit CVV2 security code, the algorithm requires a primary account number (PAN), the 4 digit expiration date, a special 3 digit service code, and a pair of DES keys. With such heavy encryption and billions to trillions of numerical possibilities, unless you have God-like mental processing power and a fleet of super computers at your disposal, you won't be able to use brute force guessing attempts to crack the codes.

While it's good to use this type of information to education yourself on the inner workings of credit cards and mathematical validation theory, it's best to stay away from trying to further crack the secret of credit card codes to come up with free workable account numbers. Don't use the Luhn Algorithm for anything else but personal entertainment and amusement.���� Please don't go around trying to generate a list of fake credit card numbers on your own and trying to buy stuff with them. I know some of you out there may be tempted to try, but you'll just get yourself in trouble.

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419 Responses to “Test Credit Card Numbers | Credit Card Validation | Money Blue Book” 

  1. jonel says:

    hi im jonel. i dont know how to process this idea. can u give me some credit cars number. thanx in return ill bless you!!

  2. John says:

    i need a valid credit card please anyone?

  3. Tony says:

    does this really work..... and can you give me a creit card number so i can use it.. thanxs

  4. yess says:

    this is insane!!
    (referring to begging comments)

  5. Segzey says:

    Plzzzzzz how can i get a visa credit card for nigerian i need it for my online study plzzzzz.

  6. moses sunday says:

    i need a valid credit card please anyone?

  7. george says:

    hi plz can u tell me how a generated cc number can work in an atm machine? secondly when using a well generated cc on the internet,what name do i use as the name of the cc account holder.plz reply.tnx.

  8. Daniel says:

    Ray,

    Thanks for sharing this rather insightful blog post about the anatomy of credit card numbers. Do you know if there are any specific differences re: the Luhn algorithm in regards to bank credit cards, department retail store credit cards, and debit cards? With the Luhn, it's possible to test credit card account numbers for validity and genuineness with the check digit test method, but are there any credit card number generating software programs out there?

    How do hackers get credit card numbers and is it possible for them to somehow generate virtual credit card numbers that actually work? I know the CCV or CCW back on the card numbers are incredibly difficult to fake and generate, but isn't it theoretically possible that at least one or two criminal fraudsters have managed to generate working credit card numbers from thin air using these brute force based credit card number generators? Also, Not every single online merchant always requires input of the secret numbers on the back of the credit card face. Isn't it still possible to get a fake credit card purchase transaction through illegally with the credit card number simulators?

    Just a thought...

  9. Pina Descolada says:

    I need fake card credit working to purchase !

    THANKS FOR U TIME !

  10. Jesus Christ says:

    My friend the blogger, I'm looking to buy a free credit card number. If you have a list of hacked credit card accounts and valid credit card numbers with cracked CVV codes, I would like to buy them as well. I am willing to pay with PayPal and offer up to $100 per account. I only offer the money because I know they are hard to get and not because I wish to steal them and use them for purchases. It is only for charitable purpose and nothing unclean

    I promise I am only asking this for research purposes as God as my witness and won't do anything illegal or bad. I'm a good Christian man from and won't resort to crooked thievery or bad acts. Not all from Nigeria or bad people I promise you!

  11. kLew says:

    Long story, but I needed to know how to identify a credit card type from the number. Your answer was very helpful. The Luhn Validation info was a bonus. Thanks! The reader comments were enough to make my eyes go crossed! You have my sympathy.

  12. Hillary thopmson says:

    What a Genius,i never could have beleived that this could be possible.Franckly speakingg,i desperately need a credit card number and full details to enable me make some online purchases.

  13. duff says:

    pls give a valid credit card num and expiring date including security code so i could make purchases on line.

  14. baloch says:

    hey frenz plz sum1 help me to give me creadit card numbers visa & master wid date expire and 3 digits number on the back

  15. risky says:

    Full Name : josie white

    ----Contact information----

    Address :224 w keeling ave
    company:
    City,State,Zip : derry , PA , 15627
    Country : United States
    Phone Number : 724-875-8531
    Email : josie.white@hardlinecomputing.

    Payment method: Credit card (Visa, Mastercard, American Express)

    Name on Card: Josie M White
    Card Number: 426429674668****
    Exp. Date (MMYY): 11/2007
    CVV2 Card Code: 291

    ##########

    Customer information

    Personal information
    Full Name : david ashwell

    ----Contact information----

    Address :123 pine haven dr
    company:
    City,State,Zip : lynchburg , VA , 24502
    Country : United States
    Phone Number : 4342370102
    Email : dlashwell@aol.com

    Payment method: Credit card (Visa, Mastercard, American Express)

    Name on Card: david v ashwell
    Card Number: 441712939421****
    Exp. Date (MMYY): 11/2007
    CVV2 Card Code: 080

    ##########

    Customer information

    Personal information
    Full Name :christina baysinger

    ----Contact information----

    Address : 805 griswold ct
    company:
    City,State,Zip : auburn, IN , 46706 ,
    Country : United States
    Phone Number : 260-235-0634
    Email : j.baysinger@mchsi.com

    Payment method: Credit card (Visa, Mastercard, American Express)

    Name on Card: christina baysinger
    Card Number: 432379303740****
    Exp. Date (MMYY): 11/2007
    CVV2 Card Code: 834

    ##########

    Customer information

    Personal information
    Full Name : KIM M FORSYTH

    ----Contact information----

    Address :15600 S.E. ANDYS CT
    company:
    City,State,Zip : MILWAUKIE , OR , 97267
    Country : United States
    Phone Number : 503-657-2601
    Email : FORSYTH358@MSN.COM

  16. Taiwo Adebayo says:

    Pls. how can i get a visa card i need it for my online study

  17. martin says:

    my name is martin taylor is me doing program in china and i win world market shanghai china in fact am not happy about cctv you people calling my name every day and every time i need my money or my china passport and my America passport you people enjoy my money in beijing but am not enjoy am sufer in side room doing program i never see any payment money only i hear about billions of dollors and billions of yuan i never see any $1 why people walked me martin handle global net work is me handle world ecomoic so is me world health and world wide watch like me hurry every day why infact only God can george now check this no money to pay my house rent no money to buy food infact i need my market document undersand me i need my payment in guangzhou i need cerdit card information

  18. Onyx says:

    This is really interesting, I never thought about using equations such as this. In fact I thought credit card numbers were for the most part completely random. Useless information if you're one of the 99% of the people who didn't bother reading the article and went straight to requesting a number. At least do the math for yourselves people, it's really quite simple! The sad part about me finding this is the fact I was looking at the Steam digital distribution platform on Wikipedia and eventually ended up looking at the phishing article which led me to credit cards and through a link there to another page which linked to yours... Keeping me up for several hours after I had planned to go to sleep. Damned Wikipedia...

  19. Wilson says:

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  20. real wayne says:

    To all those who need and have some cc for sale please do contact me fo a nice business partnerships.You can contact me on walkerlovesyou and we will chat about our needs.

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