3

Virtual / disposable / temporary / alias (all common names) credit cards frequently issue new numbers.

How is the cc company able to give out so many numbers? (Especially to a person who uses it very often.)

Do they ever run out? Each time should be different number, do they reuse numbers?

3

A credit card number contains 16 decimal digits. The first digit specifies the system, and the last is a checksum, leaving us 14 digits that we can freely use.

That's 10^14 combinations, or roughly 13.000 possible cards per human in the world. They won't run out in the foreseeable future.

Also, most virtual cards expire in a couple months, meaning that they could be reused if needed.

2

I can't speak to the entire industry since it likely varies from card issuer to card issuer. When I have used a virtual credit card, the generated number has a limited life span. It also has a credit limit that you can set. Once it the dollar amount is used up and it expires, the number is available for future usage.

1

Credit cards numbers are typically 15-19 digits long, and that's actually a lot of numbers. Not all of those numbers are available for card numbers, but each issuer still has 1 trillion numbers. One of the largest issuers, Visa, as of 2018, has approximately 755 million Visa credit cards in the world. That leaves Visa over 1,000 extra numbers per existing card to work with, but only a small percentage of people actually use virtual cards. Furthermore, virtual credit cards are typically short-lived and could be recycled, especially with revolving expiration dates.

To your point though, if every existing Visa card holder started to use virtual numbers on a day to day basis, at some point I suspect Visa would start issuing longer numbers. But I'd guess were many years away from that becoming necessary.

  • The "trillion" here is mostly a fiction -- in reality the standard's distinction between "issuer" and "account" number is not followed slavishly. For example, Danish issued VisaDankort cards all have numbers that start with 4571 followed by a 4-digit routing code for the issuing bank branch.That leaves only ten million card numbers per bank branch (still plenty, of course). – Henning Makholm Oct 24 '18 at 14:03
  • @HenningMakholm - I believe by issuer they meant "Visa", and VisaDankort would be a subset of that, still under the Visa umbrella. – TTT Oct 24 '18 at 14:35
  • Still wouldn't make the first six digits an issuer number in practice, because those digits end in the middle of the routing code. – Henning Makholm Oct 24 '18 at 15:20

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