What to Shop for in a Blackjack Game

Bona fide blackjack buffs know that some games promise more than others. Not because a dealer is hot or cold, or players at a table are making good or bad moves and therefore reinforcing or upsetting the natural flow of the cards, or other such nonsense. Rather, because certain rules reduce the casino's inherent edge.

The most patent examples are ability to resplit pairs, double-down on any two cards, and surrender bets with expected return below 50 percent. Some casinos offer options like these; others don't. Some casinos offer them only at high-limit tables.

Less evident but still common is the number of decks from which hands are dealt. The probabilities associated with the game change with this factor.

Some blackjack blue-bloods also fret over "penetration" or "shuffle-point." This is described using terms like "50-card cut-off," "4-deck penetration," or "60 percent penetration." They all tell where in the stack the dealer slips the "cut card," indicating the round after which shuffling will occur. Expressed as penetration, shuffle-point is measured from the beginning of the stack; as shuffle-point, from the end. In a six-deck shoe, 4-deck penetration, 66 percent penetration, and 2-deck cut-off are the same.

How important are these conditions? What weight should you give them in deciding where to take your action?

If you're a casual gambler - for instance if you believe it's all just luck, are guided by hunches, and bet on extra spots "to change the flow of the cards" at a cold table - your prophesies will be self-fulfilling. None of these factors matter. Go wherever the bus stops, you have a coupon, or they treat you well.

If you're a strict "basic strategy" player, ability to resplit pairs other than aces shaves the house edge by 0.04 percent, resplitting aces decreases it by another 0.08 percent, doubling after splits trims off 0.14 percent, surrender represents an 0.08 percent cut, and changing from eight to six to four decks is worth 0.03 and 0.04 percent, respectively. In an eight-deck game with doubling after splits but no resplits or surrender, the house edge is 0.48 percent. At six decks with full resplits and surrender, the edge is 0.25 percent.

Penetration has no effect on either casual or basic strategy players. However, it's a serious consideration for card counters. These players monitor what's been dealt and adjust their bets and decisions according to the cards yet to be dealt.

As penetration deepens and more cards are put into play, the chances increase that the hands dealt between shuffles will be nonrandomly distributed. The likelihood and magnitude of favorable situations increase, but the probability and severity of unfavorable conditions also rises. For solid citizens whose bets and decisions are not count-dependent, the fluctuations offset one another. For counters, who pounce when they have the edge and drop back - or out - when the odds are with the casino, there need not be a balance and the advantage can be exploited.

I'll illustrate the benefit using the six-deck game with 0.25 percent house edge. When cards to be drawn have a moderate excess of tens and aces over twos through sixes, the player has an advantage. Say a card counter knows when this occurs and bets three times as much on favorable than unfavorable hands. With 5-deck penetration, this gives the player a 0.28 percent net edge over the casino. At 4-deck penetration, the player's net edge is 0.15 percent. At three decks, it's down to 0.07 percent.

Whether, and what, to shop in a blackjack game depends on your style of play. Then again, so does your chance of winning. Sumner A Ingmark, the bettors' bard, said it well:

A gambler's notions funny,
Can cost a lot of money.