Card counting

In the United States at least, you will want to avoid trying to use any sort of electronic device to count cards. Not only is it illegal, it is also harder to look nonchalant while operating the device. Counting cards in your head isn't actually "illegal" (at least in Vegas), but the casinos that suspect you of counting cards are free to impose a lifetime ban from their blackjack tables, and to ban you from the casino completely.


Counting cards in Blackjack is a technique used to attempt to predict the average expected value of the next dealt card. Generally, the player will prefer the deck to have mostly high value cards, which increases the odds of blackjack, compared to a low value deck without any aces, for example. However, generally speaking the card counter does not keep track of the individual cards, particularly in multi-deck casino games, although the aces can be worth taking notice of.

Instead of keeping track of the individual values of the cards, the counter will generally break them into high and low categories. The simplest system is to assign a +1 to the high half of the deck and -1 to the low half of the deck. Using a wider range of values increases the accuracy but also increases the difficulty. The most accurate system, which would be more appropriate for a computer than doing in your head, would be to keep track of all 10 different possible card values.

Alternatively, another simple version would be to value the middle range cards as 0, and for example only focus on face cards and 2 thru 5, or aces and 2s, or any number of variation. The general idea will be to start at 0 (alternatively, you may wish to start at 7, which is an approximate average of the value of the card you are likely to receive in a full deck) and then increment upwards or downwards depending on the value of the card. As the value of the deck increases, you will want to bet more accordingly, or you may otherwise want to alter your play if you suspect for example you are very likely to bust when on a full deck you otherwise would not be. It is important to note dealers and other security personnel watching your game on closed-circuit cameras may notice if your strategy seems to incorporate these methods.

You'll want to take notice of the amount of decks that are in play, a game with more decks is harder to count accurately. Furthermore, you will want to forget about card counting in online casinos, as generally the entire deck is randomized between hands.