Blackjack is unusual among casino games in that the odds change with every card dealt.
In roulette, there is an equal chance any of the numbers will come up on any given spin. In craps, the possibilities remain the same on every roll.
Analysts will tell you the wheel or the dice have no memory. Past results don't influence future outcomes.
In blackjack, the cards that have already been dealt do influence future outcomes. In live games, an Ace that's dealt on one hand isn't available on the next. Either live or online, if you have a 6 in your hand, that specific 6 isn't available to be dealt again in that hand.
Those ever-changing odds are the basis of card counting in live casinos. Advantage players bet more when the composition of the remaining deck is in their favor and less when the odds turn against them.
Online players can't take advantage of that. Cards at online casinos usually are shuffled for every hand. But even online, there are a few instances where straying from basic strategy can bring you a small gain.
Interesting Hands to Consider
The online gains come in the form of composition-dependent strategies. A prime example is hard 16, where 10-6 and 8-5-3 have the same total, but carry different odds.
That affects strategy when the dealer has a 10 face up. Basic strategy calls for players to hit hard 16 against a dealer's 10. The likelihood of the dealer making a standing hand of 17 or better to beat 16 is high enough that it overcomes the reluctance to risk busting with a hit.
Hard 16 vs. 10 will lose more than it wins no matter what you do, but if it consists of 9-7 or 10-6, your average losses will be slightly lower if you hit than if you stand. With the other two-card 16, 8-8, the best option is to split the pair.
The situation changes when the 16 is composed with three or more cards. Let's use the 8-5-3 mentioned earlier as an example. In a six-deck game in which the dealer hits soft 17, you'll lose an average of 54.4 cents per dollar wagered if you hit. If you stand, that average loss dips to 54.0 cents.
That's the opposite of the situation with two-card hard 16s. The gain is small, but with 8-5-3 vs. 10 the better play is to stand.
More Strategy Thoughts
Best strategy shows the same flip anytime you have a hard 16 consisting of three or more cards that include one or more 4s or 5s.
The reason is having that 4 or 5 already dealt and not available for a hit reduces the chances of drawing a card that will give you 20 or 21 – and increases the chance of busting – just enough that standing vs. 10 becomes the better play.
The numbers given are for six-deck games, but the same applies to the single-deck games found more often online than in live casinos.
Another composition-dependent play applies to single-deck games where the dealer hits soft 17 but not six-deckers, and that means online players will benefit a lot more often than those who play in live casinos. However this is a move to make in less common six-deck games in which the dealer stands on all 17s.
If you have hard 12 and the dealer's face up card is a 4, basic strategy calls for you to stand. That holds up if your 12 is 9-3, 8-4 or 7-5.
However in a single-deck game, if you have 10-2 vs. 4, the better play is to hit. Average losses on 10-2 vs. 4 are 20.7 cents if you stand, but 19.4 if you hit.
Because your hand already has a 10, there's one fewer 10-value card available for a draw that would bust you. That's enough to shift the strategy with a single deck, but doesn't move the odds enough to make the switch in a six-deck, hit soft 17 game. Do switch to hitting 10-2 vs. 4 with six decks if the dealer stands on all 17s.
Live Casino Strategy & Advantage Play Considerations
Players in live casinos have expanded strategy shift opportunities. Much of that comes via counting cards, which is a topic unto itself. But even non-counters can make small gains by watching other players' cards.
That's easy enough to do in common six-deck games. Player cards are dealt face up.
Fred Renzey, author of "Blackjack Bluebook" and "Blackjack Bluebook II" emphasized giving players small steps they could use to improve their games before attempting full card counting.
Among those ways were table-dependent strategies, with seven close-call hands.
Notice that two of the hands are the 16 vs. 10 and 12 vs. 4 already discussed as composition sensitive even if you're just watching your own hand and the dealer's up card.
If you're playing a six-deck game where all player cards are dealt face up, think about these potential changes that reverse basic strategy plays.
- Hit hard 12 vs. 4 if the cards on the table, including all player cards and the dealer up card, include more 10-value cards than 2s, 3s, 4s or 5s.
- Stand on hard 16 vs. 10 if there are more 2s-5s than 10 values.
- Hit hard 13 vs. 2 if there are at least five more 10-value cards than 2s through 5s.
- Double down on hard 9 vs. 2, Ace-8 vs. 5 or Ace-8 vs. 6 if there are at least five more 2s through 5s than 10 values.
- Double down on 11 vs. Ace with at least six more 2s-5s.
Sometimes the switch is because cards already played make it less likely you'll bust. Sometimes it's because they make it more likely you'll make a good hand. The effect cards already played have on the dealer's hand also is a factor.
Card counters have many more opportunities to gain with plays that differ from basic strategy. With a commonly used counting system called "Hi-Lo," players speak of an "Illustrious 18" hands in which cards already played frequently lead to strategy changes.
One example: If there is one deck remaining to be played and three more low cards than high cards already have been dealt, then it becomes advantageous to take insurance.
A basic strategy player skips insurance, but with a great enough concentration of high cards remaining, dealer blackjacks become more likely.
Non-counters should continue to skip insurance. So it goes with other plays that help counters. If you don't track the balance of high and low cards, you're better off sticking with basic strategy than trying to guess or estimate.
But for the composition-dependent hands and the table counts listed earlier, you have all the information in front of you as you play that hand. Gains are small, but easily available.