How to decode credit card numbers

Originally published at: How to decode credit card numbers | Boing Boing


the tl;dr of it:

the first six-seven digits indicate who issued the card (the issuer Identification Number)
of that, the first digit indicates the general industry the card issuer is in (airlines, travel, etc.)
the remaining digits indicate the credit network (visa/mastercard) and issuer
the second nine- twelve digits indicate the account number within the credit network.
the last digit is the check digit and verifies if the card number is correct.

It’s kind of neat, in a nerdy way. There’s also an ISO standard for it.


And of course all Amex cards start with 3, all Visa cards start with 4, and all Mastercards start with 5.

Is the place I go when I need to register these number just to access a website.


I use these “valid” credit card numbers when dealing with scammers on the phone. It really prolongs the call with confusion about why my card isn’t working.


Discover and private label merchandisers (gift cards for example) start with 6. There is a defined standard for card transactions called ISO 8583 which card processors develop their authorization systems against.


Does that work for YouTube? It’s started to ask me to verify my age in case I get upset by music with Bad Words in it, but am I fuck giving it my card details just to watch old slayer videos.

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kinda like barcodes…

I was wondering that too. Just tried it and my card was declined :pensive:

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