Multi-Deck Card Counting

Blackjack is a popular casino-banked game that can utilize anywhere between one and eight decks of cards. The cards are typically not reshuffled after every round of play which renders 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 what their odds of winning a given round are. It is a mathematically proven fact that in blackjack, the excess of high cards that remain to be played tips the odds in favor of the player. And vice versa, the excess of low cards shifts the advantage in favor of 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 through counting. One of the first things they did was increase the number of decks in play. Little did they know this was nothing but 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?

blackjack countingCard counting is veiled in myths and misconceptions, which result largely from 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 the autistic character of Dustin Hoffman crushes the blackjack tables at Caesars Palace through counting, one of the members of the casino’s surveillance team exclaims 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, the betting session starts with players keeping track of each dealt card that appears on the table. Each card is assigned a count value which depends on the counting system one uses. The most popular system in use is the Hi-Lo where the Kings, Jacks, Queens, 10s, and Aces have a count value of -1, the small cards 2 through 6 have a count value of +1, and the neutral cards 7, 8 and 9 are counted as 0.

Blackjack Card Counting Gameplay


Running Count to True Count Conversion

blackjack card countingThe 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.

Just to give you an 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 equal to +8/4 = +2. If the running count is negative, say -8, so will be the true count (in this case -8/4= -2).

It is obvious those who play shoe games should also learn to accurately determine the number of undealt decks. 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 only have to subtract the number of the remaining decks from the total number of decks the game started with.

A Tip on Practicing Accurate Deck Estimation

Practicing blackjack card countingCounting 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 stack contains two decks, the third contains three decks and so on. You can label each stack so you know how many decks are in there. You put any one group of cards on the table, inspect it closely for some time and try to determine the number of decks in contains.

Try to do it without looking at the labels. Then you 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 how accurate you can get when you put in enough practice.

The Card Counter’s Advantage in Multiple-Deck Blackjack

blackjack house edgeIt is mathematically established that each one-unit increase in the true count yields a half-a-percent increase 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 whatsoever 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 players’ edge increases proportionately to the true count so you get 1% advantage on a true count of +3, a 1.5% on a true count of +4, a 2% advantage with a true count of +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

blackjack bet sizeCard 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 sizing on the basis of 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 higher chances of being detected and backed off, even though counting cards itself is not deemed an illegal practice. Some blackjack experts recommend using a 1-12 bet spread for shoe games where six and eight decks are in play.

Varying Your Playing Decisions with the Help of the True Count

blackjack playing decisionsMore 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 increases (or decreases) significantly, the recommended basic strategy moves are no longer optimal.

This makes sense because basic strategy takes into consideration only three cards, those in your starting hand and the upcard of the dealer. Some advantage players memorize 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 by giving you 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 an excellent 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 stands better chances of busting with a 6 than outdrawing you.

However, if you count the cards and arrive at a true count of +5 or higher, this serves as an indicator 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 for the purpose of extending their longevity.

Mr. Schlesinger also developed several indices designed to help advanced players with their surrender decisions. These are again to be found in his Blackjack Attack – Playing the Pros’ Way book 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 TC of positive counts; Hit at -1 or lower
15 vs. 9 2 Surrender at TC of +2; Hit at TC of +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.

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Dan Janet

What is the ideal number of decks used in blackjack for card counting?

Asked by: Janet | Asked on: 2023-06-14
Answered by: Dan | Answered on: 2023-06-15

Generally speaking, the fewer decks are used in the game, the better it is for card counters. A low number of decks gives players fewer cards to keep in mind, which also makes card counting more accurate. That is why blackjack games with a single deck are the best options for card counters. However, casinos are also aware of that, which is why you can rarely find single-deck versions of the game of 21 that use player-beneficial rules. Most commonly, single-deck variants will offer a blackjack payout of 6 to 5, which is a rule you should avoid like the plague. In such a case, it is better to choose a game with two or more decks. Keeping a true count may be more difficult to achieve but at least you will play with better potential return.