Although hitting and standing are the most common actions taken when playing Blackjack, doubling down is where much of the opportunity for profit lies. To “double down” means to increase the size of one’s bet after the first two cards have been seen, in return for one more card, and only one more card. The most favorable situation for doubling down is when the dealer is showing 2~6 as the up card and the player is holding a count of ten or eleven and drawing a 10 or a face card would result in a hand worth twenty or twenty-one.
The maximum one can increase the bet by when doubling down is an amount equal to the initial wager. This is certainly the most common amount staked, but it is also possible to double down “for less.” This is done by wagering at least the table minimum and no more that the amount initially bet and clearly saying to the dealer “For less.” This action may occur when a player is short on chips and cannot venture the full double or when confidence in the result is low, such as doubling down on a hand valued at hard twelve or higher.
Most casinos, such as those on the Las Vegas Strip, allow players to double down on any two cards. Some restrict the practice to hands valued at nine, ten, or eleven. Many permit doubling down after a split, which very advantageous to the player. A few allow doubling down at any time, on any number of cards, but in such instances there is usually some sort of trade off, such as blackjacks paying on 1-to-1 instead of 3-to-2 or the dealer winning on all pushes. The House Rules must be studied closely.
Doubling down on hard totals of twelve or more is generally not advisable, owing to the risk of busting on the next card dealt. Similarly, doubling down on a hand valued at four or five cannot result in a count of seventeen or more, so it is considered an extremely poor action. For hands valued at six through eight, the odds are against a favorable draw, so there are few situations that would warrant such risk. And with the exception of a pair of 5s, splitting small pairs is usually preferable to doubling down.
A special case for doubling down regards “soft” hands containing an Ace counted as eleven, and they are treated differently. When holding a soft total of thirteen to nineteen, the player may look to double down. There is no risk of busting.
Doubling Down Strategy
Making a decision about when to double down is not simply a matter of whim or hunches. Much of it depends on what card the dealer is showing and how many decks are in play. For example, Basic Blackjack Strategy calls for doubling down when playing a single-deck game and holding a total of nine facing a dealer’s 2~6. When playing with four or more decks, the strategy must be altered slightly, hitting against the dealer’s 2 instead of doubling down.
For those who like to keep things simple, the general rule of thumb is to always double down when holding a hand worth eleven facing any up card, with the exception of an Ace if insurance is not available. Also, always double down when holding a count of ten against the dealer’s 2~9 and when holding nine against the 3~6. Never down double down on any pair other than 5s.
For soft hands, again keeping it simple, always double down against the 5 or 6 when dealt a soft total of thirteen to eighteen. Double down against the dealer’s 4 when holding a soft hand valued at fifteen through eighteen, and against the 3 when holding soft seventeen or eighteen. Never double down with a total of soft nineteen or twenty; instead, always stand.
It is important to note that the House Rules also have an effect on strategy, because they impact Blackjack odds by either increasing or decreasing the house advantage. If a player is allowed to double down after a split, for example, the house edge reduces by 0.13%. But if the rules prohibit doubling down on any total other than ten or eleven, the margin increases by 0.21%. Finding a table with favorable doubling down rules should be the goal of any serious Blackjack player.