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The Effects of House Rules

The most common way for a casino to manage its desire to turn a high profit against the player's demand to have a fair chance at winning is to adjust the rules of the game, increasing or decreasing its own advantage. Here are the effects that various rules have on the outcome of the game:

Wagering Limits

Setting a minimum limit to wagering amounts does not affect the outcome of hands played at the table, but it does affect the amount of profit the casino will take from the players. Simply by raising the table minimum from $5 to $10 will double the profit that will be turned.

The table maximum likewise has no effect on the outcome of hands, but neither does it improve the house's profits. Table maximums were implemented in order to defeat the Martingale system, a highly effective strategy (discussed in the intermediate strategies section of this site).

But by far, the most effective wagering limitation casinos employ is the option to refuse to allow a player to wager at all—in effect, to throw him out of the game, or even the casino. Regardless of the strategy a player utilizes, he can expect to be asked to leave the table (or forcibly ejected) if he seems to be winning consistently. Though it's certainly not something the casino industry wants to be known, the best strategy for a casino to make profit is to allow only losing players to participate, and show winners to the door.

Decks Per Shoe

Increasing the number of decks per shoe would not seem to affect the outcome of the game: no matter the number of decks, the proportion of cards in the deck remains the same. There remains a 1 in 13 chance that a card of a specific type will be drawn for the next hand or the next hit. The reason is a bit convoluted:

Once the first card has been dealt, it is no longer available, so the odds of drawing a card of the same value (making a pair) are less. To be precise, the odds are 3 in 51 (about 1.8% less) in a single-deck game, 7 in 103 in a double-deck game (1.2% less), and so on, with the odds diminishing as more decks are added. As more cards are drawn, the odds are further skewed.

Though pairs are "exciting" to the player who expects to win both hands, this is not the most likely outcome. In most cases, pair-splitting is done to salvage a bad hand, in hopes of winning only one of the split hands to break even. As a result, the more decks, the more pairs, and the more risk a player must assume in unfavorable situations, just to break even.

Pairs are also likely to show up on the dealer's side. Although the dealer cannot split pairs to salvage the round, neither does the house lose twice as much when both split hands lose—so the effects of an increased incidence of pairs are not the same on both sides of the table. Though the house may lose a greater number of hands that begin with paired cards, it will lose less money when these losses occur.

The effects of increased pairs to the player's odds are:

Limiting Options: Surrender

It is in the player's surrender in situations in which his chances of winning are less than 50%. Typically, the player is allowed to surrender on the initial hand ("early surrender") and, in rare cases, a player may surrender late. The option to surrender may be restricted according to the value of the dealer's upcard. The effect of surrender variations on the core odds are:

Limiting Options: Doubling

A player's ability to double has a dramatic affect on a player's potential winnings—but also has a dramatic effect on his losses. In general, the ability to double on any initial hand (including split hands) increases the player's advantage by 1.83%. Naturally, many casinos seek to recapture this margin by limiting the player's opportunities to take advantage of doubling.

In rare cases, the house may allow a player to "double late"—adding the option to double after the hand has already been hit. When this option is available, it increases the player's advantage by only 0.20% (as it's rare that a third or fourth card will yield a hand that should logically be doubled).

Limiting Options: Splitting

In the typical game, a player may split up to four times. In a single-deck game, this is the absolute limit, as there are only four cards of a value in the deck. In multiple-deck games, the likelihood of being able to split a fifth, sixth, etc. time is so remote that the on the odds is negligible. If a player may split only once, however, the effect on his advantage is -0.10%

Also, it is typical for the player to receive only one card on split aces, and not to be able to split them further. If allowed to take hits split aces, the player gains an advantage of 0.14%—and if allowed to re-split them if another ace is drawn, and additional 0.03%.

Altering Blackjack odds or payoffs

Blackjack typically pays at 3:2 odds. In rare cases (such as special promotions), a casino may offer 2:1 payoffs, which increase's the player's advantage by 2.32%. Most often, the increased payoff is on "suited blackjacks"—in which the ace and ten-value card are of the same suit. As only 1 in 4 blackjacks are likely to be "suited", the net gain is %0.58.

Another rare variation is "no hole card"—in which the dealer does not receive a second card until all hands are played (or "no peek", in which the card is dealt, but not checked), and a blackjack at that time claims all increased (doubled, split) bets. This decreases the player's advantage by 0.13%.

Altering Dealer Play

One variation that's common, especially in single- and double-deck games, is that the dealer will hit a soft 17. This increases his odds of busting, but it also increases his odds of drawing to a higher hand. The net effect is a loss of 0.21% to the player.

Dealer Wins Pushes

An exceptionally greedy house will change the rules of the game—so that a player who does not beat the dealer's hand will lose his wager, even if the hands are of equal value. This has a devastating effect on a player's odds (decrease by 9.4%). To increase the take without scaring off all the players, the house may declare that the dealer wins only certain ties:

Calculating the net effect

Since many factors are involved, it is impossible to display all possible combinations without an unfathomable convoluted matrix. Instead, an Odds Calculator (JavaScript) is provided to explore the results of all possible combinations.

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