Blackjack is a popular casino-banked game that can be played with anywhere from one to eight decks of cards. The cards are typically not reshuffled after every round of play, which makes the game susceptible to advantage-play techniques such as card counting.
This method enables skilled players to track the ratio of high to low cards, which gives them an accurate idea of their odds of winning a given round. It is a mathematically proven fact that in blackjack, an excess of high cards yet to be played tips the odds in favor of the player. Conversely, an excess of low cards shifts the advantage to the house.
Card counting first gained notoriety in the early 1960s after the publication of Edward Thorp’s bestseller Beat the Dealer. The book became an overnight success and scared casino operators into changing the rules of the game in an attempt to prevent players from beating it by counting. One of the first things they did was increase the number of decks in play. Little did they know it was merely a small bump in the road for card counters, who continue to crush the game of 21 to this day.
Is It Possible to Count Multiple Decks in Blackjack?
Card counting is shrouded in myths and misconceptions, largely because of the way this advanced method is portrayed in media and movies. Passed from one generation to the next, these misconceptions prevent many people from learning how to become profitable blackjack players.
The infamous scene from the Academy Award-winning motion picture Rain Man serves as a classic example. When Dustin Hoffman’s autistic character crushes the blackjack tables at Caesars Palace through counting, one of the casino’s surveillance team members exclaims that no person in the world could possibly “count into a six-deck shoe.”
Luckily for card counters worldwide, there is not even an ounce of truth in this statement. Card counting can be just as effective in shoe games as it is in single-deck blackjack. It simply requires a slightly different approach.
Either way, a betting session starts with players tracking every card dealt at the table. Each card is assigned a count value, which depends on the counting system you use. The most popular system in use is the Hi-Lo, where Kings, Queens, Jacks, 10s, and Aces have a count value of −1, the small cards 2 through 6 have a value of +1, and the neutral cards 7, 8, and 9 are counted as 0.
Counting Multiple Decks in Blackjack: Additional Tips Keeping track of each dealt card helps the player establish their running count, which gives them a reasonably accurate idea of the composition of the remaining deck. This running count should be maintained throughout the entire course of the game until the dealer shuffles again.
The player uses the ratio of high to low cards to determine their edge and sizes bets in proportion to it. So, for example, if the cards K, 10, 2, 8, and 6 appear during the first round, you end up with a running count of 0 because the high and low cards cancel themselves out. The 7 is neutral and, as such, has no effect on the running count. The odds have not yet swung in your favor, so you should not increase the size of your next bet.
However, maintaining a running count alone is not enough to determine your advantage accurately when multiple decks are in play. A high positive count of +5 after the first round of play gives a single-deck player a considerable advantage over the house, which, in turn, justifies a significant bet increase on the next round.
This is not the case with a positive count of +5 when one plays against six decks. The edge it gives you is less significant because more than five and a half decks are still in play. To arrive at an accurate estimate of their edge, multiple-deck players must convert the current running count into a true count per deck.
Blackjack Card Counting Gameplay
Running Count to True Count Conversion
The conversion of the running count into a true count is not as scary as it sounds, but more importantly, it does not require you to be a savant like Dustin Hoffman’s character in Rain Man. The true count denotes the density of high or low cards per deck. You arrive at an accurate true count after you divide the running count by the number of undealt decks.
For example, suppose you are playing blackjack with eight decks and have reached a running count of +8 while there are four undealt decks in the shoe. In this case, the true count is +8/4 = +2. If the running count is −8, the true count will also be negative (−8/4 = −2).
It is obvious those who play shoe games should also learn to determine the number of undealt decks accurately. You use the discard tray, positioned at the dealer’s right side, for this purpose. The discard tray enables the dealer to stack the dealt cards neatly so that they are clearly visible to everyone at the table. Deck estimation requires a lot of practice, but once you master it, you simply subtract the number of remaining decks from the total number of decks the game started with.
A Tip on Practicing Accurate Deck Estimation
Counting into multiple decks of cards is not rocket science, but it still requires a good amount of discipline and persistence if you insist on accuracy. Once you master maintaining an accurate running count, you need to practice your deck estimation. One approach recommended by blackjack experts is to purchase a discard tray and fifteen standard packs of cards.
You should divide the packs into five separate stacks, where the first stack contains a single deck, the second contains two decks, the third contains three, and so on. You can label each stack so you know how many decks are in there. Place any one group of cards on the table, inspect it closely for some time, and try to determine the number of decks it contains.
Try to do it without looking at the labels. Then place the groups of cards, one at a time, in the discard tray and practice deck estimation by inspecting the height of each stack. It sounds more difficult than it really is. You will be surprised at how accurate you can get when you put in enough practice.
The Card Counter’s Advantage in Multiple-Deck Blackjack
It is mathematically established that each one-unit increase in the true count yields an increase of half a percent in the player’s advantage. The conclusion we can draw is that a person playing a six-deck game where the house edge is roughly half a percent has no advantage at a true count of +1.
Respectively, you gain an advantage of half a percent when you arrive at a true count of +2. The player’s edge increases proportionately with the true count, so you gain an advantage of 1% at +3, 1.5% at +4, 2% at +5, and so on.
The bigger your edge gets, the higher the amounts you should wager. The majority of experienced blackjack players choose to size their bets according to a betting technique known as the Kelly Criterion. This approach enables them to maximize their profits and reduce the risk of losing their bankrolls at the same time. The edge players manage to get in blackjack is not all that substantial, so one should not expose large portions of their bankroll to risk during any given round of play.
Adjusting Your Bet Size in Multiple-Deck Games
Card counters gain an edge in blackjack by sizing their bets proportionately to the count. They increase their wagers when they have the edge and bet the table minimum, or nothing at all, when the casino has the edge. This practice of sizing your wagers based on the true count is called spreading your bets. When choosing a bet spread, players should ask themselves two questions: “What bet spread is required to beat a given multiple-deck game?” and “What bet spread will allow me to play and count cards undetected?”
Casinos are no strangers to how blackjack works, and their employees are well-trained to detect card counters. If you spread your bets too aggressively, you stand a higher chance of being detected and backed off, even though counting cards itself is not illegal. Some blackjack experts recommend using a 1-12 bet spread for shoe games where six and eight decks are in play.
Adjusting Your Bet Size in Multiple-Deck Games Additional Tips Assuming you play at a table where the minimum is $5, you should start the session by betting one unit, or $5, when the count is negative, zero, or +1. You continue flat-betting $5 until the true count rises to +2, at which point you increase your bet to two base units, that is, $10 on the next hand.
When you arrive at a true count of +3, you wager four base units, or $20. The shoe continues to grow hot, and you reach a true count of +4, which calls for a bet increase to eight units, or $40. After the true count reaches +5 or higher, you bet in increments of 12 units, or $60.
This betting ramp is considered ideal for multiple-deck games. Whether you get labeled as a card counter largely depends on the tolerance level of the casino where you are playing. Smaller establishments are more likely to back you off, so you might want to choose a more conservative spread in this case.
Varying Your Playing Decisions with the Help of the True Count
More experienced counters further increase their advantage by varying their playing decisions according to the true count. These departures from basic strategy on the basis of true count are known as indices. They are very important because when the true count changes significantly, the recommended basic strategy moves are no longer optimal.
This makes sense because basic strategy considers only three cards: those in your starting hand and the dealer’s upcard. Some advantage players memorize more than 100 index plays, but this is hardly necessary to gain a good edge in blackjack. In fact, using only the indices listed below can significantly improve your play.
The 18 indices listed in the first table are known as the Illustrious 18 and are intended for multiple-deck blackjack games where the dealer stands on soft 17. They were developed by the renowned Blackjack Hall of Fame inductee Donald Schlesinger and help you make more accurate insurance, standing, doubling, and splitting decisions. You can find more about these indices in Mr. Schlesinger’s book Blackjack Attack: Playing the Pros’ Way.
| Player Total vs. Dealer Upcard | True Count (TC) | Recommended Playing Deviation |
|---|---|---|
| Insurance bet | 3 | Buy insurance at TC of +3 and above |
| 16 vs. 9 | 5 | Stand at TC of +5 and above |
| 16 vs. 10 | 0 | Stand at TC of 0 and above |
| 15 vs. 10 | 4 | Stand at TC of +4 and above |
| 13 vs. 2 | -1 | Stand at TC of -1 and above |
| 13 vs. 3 | -2 | Stand at TC of -2 and above |
| 12 vs. 2 | 4 | Stand at TC of +4 and above |
| 12 vs. 3 | 2 | Stand at TC of +2 and above |
| 12 vs. 4 | 0 | Stand at TC of 0 and above |
| 12 vs. 5 | -1 | Stand at TC of -1 and above |
| 12 vs. 6 | -1 | Stand at TC of -1 and above |
| 11 vs. Ace | 1 | Double at TC of +1 and above |
| 10 vs. 10 | 4 | Double at TC of +4 and above |
| 10 vs. Ace | 4 | Double at TC of +4 and above |
| 9 vs. 2 | 1 | Double at TC of +1 and above |
| 9 vs. 7 | 4 | Double at TC of +4 and above |
| Pair of 10s vs. 5 | 5 | Split at TC of +5 and above |
| Pair of 10s vs. 6 | 5 | Split at TC of +5 and above |
Let’s explain how you should approach this chart with an example. Suppose you are dealt a hand of paired Queens against a dealer who shows a 6. This is an excellent hand to get, even more so when the dealer is in a vulnerable spot with this small upcard.
A basic strategy player should never touch this hand. It gives them a total of 20, and the only way for the dealer to beat this is by drawing to 21. The chances of this happening are not significant. Quite the opposite, the dealer is more likely to bust with a 6 than to outdraw you.
However, if you count the cards and arrive at a true count of +5 or higher, this indicates the shoe is richer in ten-value cards. This knowledge allows you to maximize your value by splitting the Queens and potentially winning two hands instead of one. That being said, the majority of professional card counters prefer to refrain from using this index to extend their longevity.
Mr. Schlesinger also developed several indices designed to help advanced players with their surrender decisions. These can again be found in his Blackjack Attack: Playing the Pros’ Way and are known as the Fab 4 indices. You can see them in the table below.
| Player Total vs. Dealer Upcard | True Count | Recommended Playing Deviation |
|---|---|---|
| 14 vs. 10 | 3 | Surrender at TC of +3 or higher; Hit at TC of +2 or lower |
| 15 vs. 10 | 0 | Surrender at positive counts; Hit at -1 or lower |
| 15 vs. 9 | 2 | Surrender at TC of +2; Hit at +1 or lower |
| 15 vs. Ace | 2 | Surrender at TC of +2 or above; Hit at +1 or lower |
One way to memorize these playing deviations is by using flash cards. But before you get there and make any attempts to count into multiple decks, you should make sure you know perfect basic strategy and can maintain an accurate running count. Messing up the running count would lead to inaccuracies in your true count, which, in turn, would render your efforts at beating the game of blackjack futile.