To compute Blackjack odds, you first need to know what version of the game you are playing. How many decks are being used? Does the dealer stand on soft 17? Is it possible to double down on any combination of two cards? Can you re-split Aces? Surrender? Does the casino pay a bonus for a suited 6-7-8? One estimate puts the number of possible rule combinations at close to 7,000.
One thing you know for certain, no matter what version you play, is that the house must have an advantage over the player; else the game’s organizer would soon be out of business. Knowing how much that advantage is can have a huge affect on where and how you play.
Very few casinos today still offer single-deck Blackjack with classic rules and payouts. There is a good reason for that. A card counter who follows the Basic Strategy of play can actually take away the house edge.
For example, consider a single-deck game where the dealer stands on soft 17, shuffles after every hand, and allows doubling down not only on any two first cards but also after a split. Optimum play would give the player an overall edge of 0.15%. In fact, even an average player would find this to be a profitable game, with no built-in advantage for the house.
But as you know, the house must have an edge, so the rules are changed to pay 6-to-5 for a natural blackjack on the first two cards instead of the customary 3-to-2. You might think such a small change would have very little effect on the odds. In reality, it shifts the game odds to the house by 1.24% against even the strongest player.
Or suppose the blackjack payout remains 3-to-2, but the house uses four decks instead of just one. That small change results in a house edge of 0.44%. Make it six decks and the advantage rises to 0.48%. And at eight decks, the house edge is 0.50%.
Going back to the single-deck game, what if the house has its dealers hit on soft 17 instead of standing? Again, you might think it has a negligible affect, but the odds swing in the house’s favor by 0.19%. Or if the rules take away the player’s ability to double down after a split, that’s worth another 0.13% to the house.
As you can see, small adjustments in the rules can affect the odds in a big way, as can small adjustments to the way you play your hands. Some Blackjack strategies reduce the house edge, while others simply add to its advantage.
As a case in point, let’s use a casino offering four-deck Blackjack with “liberal” Atlantic City rules, where the dealer stands on soft 17. The player can split up to four hands, double after a split, and double on any first two cards. The house’s edge is about 0.44%.
If the player uses a common beginner’s strategy called “never bust,” refusing to hit any card total of hard 12 or higher, the house advantage increases to 3.91%. If the player chooses to “mimic the dealer,” playing exactly the way the dealer plays and never doubling or splitting, the house edge shoots up to 5.48%.
On the other hand, a player who counts cards and plays the Basic Strategy can turn the house advantage on its head at certain points during the game. Lawrence Revere, author of the classic bestseller “Playing Blackjack as a Business,” estimated that “just by keeping track of the 5’s, for example, you sometimes have an advantage of 3.6% over the house.” Those who count tens or use a “Plus Minus” counting system can drive the odds even higher.
So before you sit down to play Blackjack, give some serious thought to the odds and the two ways in which you can improve your chances of winning. Choose a table with rules that favor the player, and use Basic Strategy when you play.