If card counting in blackjack is just keeping track of high cards vs low, does that mean if I could remember all the different cards used (i.e. how many 5s, how many 7s) I would be really good at blackjack?

995 viewsMathematicsOther

This would break online casinos because you could easily do that with electronics. Assuming the casino itself is playing fair.

If you could perfectly keep track of how many of which cards are left in the decks, and everytime make the most mathematically sound bet, would the house still have an edge?

(I assume the correct answer will start off saying I don’t understand how card counting works – fair enough, but what about the basic explanation of it did I misinterpret?)

In: Mathematics

37 Answers

Anonymous 0 Comments

Technically yes, the more detailed information you can obtain about the game, the more precisely you can estimate where the house edge is at any time. The concept of diminishing returns is still present though. For example, the difference in the effect of a 2 or 3 being removed from the remaining shoe, for all practical purposes, is effectively the same.

However, when tracking individual cards, the math starts getting extremely complicated, and easily impractical in live games due to the time it takes.

Anonymous 0 Comments

Most places these days use automatic shufflers that run way too often for a true edge to ever build up.

Anonymous 0 Comments

The house doesn’t even have an edge when you use simpler card counting techniques. That’s why casinos don’t want to play with card counters. If you were to know the precise composition of the remaining cards in the shoe and mathematically calculate the best bet size and strategy adjustments, yes, you will have an edge. However, that’s a lot of mental work for marginal increases in advantage over popular card counting systems.

Anonymous 0 Comments

The information becomes more actionable and thus valuable the further into the shoe you are. Casinos don’t use all the cards. They only use a portion of the shoe and then reshuffle. You would certainly gain more of an advantage if you could remember every card that had been dealt.

Not sure how online casino blackjack works.

Anonymous 0 Comments

I’ll preface this by saying that I don’t know how frequently every online casino would re-shuffle the deck, but any information that you gained by card counting would be erased once the deck is shuffled and you’re starting from scratch again. If this happens after every hand, you won’t learn enough about what’s left in the deck to be able to use that knowledge in any meaningful way.

Anonymous 0 Comments

Pretty sure online casinos use like 10 decks and still shuffle every few hands. That’s an exaggeration of course, but they shuffle way more often than a live casinos, and some use automated shuffle machines.

When playing blackjack, they add a card into the shoe and when it’s drawn, they re-shuffle. It’s placed really close when playing online.

Anonymous 0 Comments

>If you could perfectly keep track of how many of which cards are left in the decks, and everytime make the most mathematically sound bet, would the house still have an edge?

Your understanding of card counting is correct — keep track of the cards that have been played, use that information to figure out the odds of your success (or failure), then adjust your betting to improve your odds of losing small (…and thereby winning big), ie: don’t raise when your odds of success are low, raise when your odds are higher.

The more cards you *see* played, the better you know the cards that are left, and the stronger your model becomes. Let’s say from a fresh deck, you are dealt a 12 and you don’t see any face cards or 10’s on the table. You have *almost* no idea if hitting on your 12 will bust or not. Later in the game, from that same unshuffled deck, if all face cards and tens have been played, you can be 100% certain that hitting on 12 won’t bust.

In order to maintain quick play (not have to shuffle between every hand) *and* somewhat foil card counters, casinos use multiple decks. So instead of keeping track of the cards in 1 deck, you now have to keep track of the cards in 4+ decks. As before, at the beginning your model will be weak and it will get stronger until the decks are shuffled again.

>This would break online casinos because you could easily do that with electronics. Assuming the casino itself is playing fair.

Card counting *only* works when you are playing from a *known* deck of cards. With online casinos there are no decks. Every hand is ‘shuffled’, so any model you make can only be made from the cards you *see currently* on the table, and that doesn’t give you much information about what cards are left to be played. Essentially, card counting doesn’t work with computerized games.

Anonymous 0 Comments

If online games didn’t shuffle the deck, yes. But since the cost of shuffling the deck in an online game is zero, they “shuffle” after each hand. So, no, you cannot card count at online casinos.

Anonymous 0 Comments

AFAIK card counting works best when you have a single deck of cards, because you have a limited set of cards to work through. If you’ve seen all the Jacks, you know there’s no more Jacks until the deck is shuffled again.

Casinos know this and use 6-8 decks per table. Now you have 24-32 Jacks to keep track of.

You’re also assuming that you will play the whole deck. There’s a number of triggers that might make a dealer shuffle, so you might only get half way through a single deck before it gets shuffled. With an 8 deck shoe, you might only get through 1-2 decks worth before it shuffles.

A lot of this is tied to the limitations of a human dealer. Shuffling takes time so more shuffles = fewer hands = less profit. With electronic poker, they can reshuffle every hand if they want.

Anonymous 0 Comments

Card counting works as you said, track the number of high/low cards. In a casino, there are many decks in play, and they are reshuffled frequently to inhibit card counting.

With online play, my assumption is there is no situation where the same set of decks are used between hands because they shuffle every time. Just a guess though.