Many casinos allow blackjack players to double down on any two cards or to DOA, while some will restrict doubling to hands that total ten or eleven only. Obviously DOA is a far more favorable strategy as far as the blackjack player is concerned. One other favorable strategy for the player is when you are allowed to double after splitting or DAS. These two types of doubling down in blackjack affect the house edge in different ways.
In a blackjack shoe game played with eight decks where you can double on anything, the house advantage is only a little more than half of 1%. In addition, there are other rules that pertain to doubling that can either serve to reduce or increase the basic house advantage.
Basic strategy can also be used when playing blackjack in order to determine when the best time to double down is depending on the mathematics of the game. One of the main reasons why doubling down is such a good idea is that you are actually doubling your bet when the best opportunity to beat the dealer presents itself. More often than not, this opportunity comes up when the dealer is at their most vulnerable point. In many cases, this happens when the dealer displays an up card that can cause them to bust.
Over the years, a number of computer simulations have been performed for the purpose of determining how often a dealer will bust based on their up card. Based on these studies, it appears that the worst cardsľat least as far as the dealer is concernedľare the cards from two to six. When these cards are displayed, the tendency is for the dealer to bust, and this is then a good time to double down.
There are other situations in blackjack when it would be beneficial for the blackjack player to double down with a ten card against a nine card of the dealer, or an eleven card against a ten card of a dealer. These are some pretty hit or miss situations however, and as such many new blackjack players are quite hesitant to do this, leaving it instead to the more experienced blackjack players. In any case, it would be beneficial for all blackjack players to adopt this strategy, since it can still result in a certain degree of success for the blackjack player, although admittedly not as many time as when the dealer has a smaller card in his hand. The bottomline is that you can stand to win more money in the long run by adopting this strategy than you would of you did not. Remember: doubling down at the right time ensures that you are playing correct basic strategy and thereby decreasing the house edge.