Introduction to Card Counting

It is no secret that in order to manage to win consistently at Blackjack, players need to follow a reliable strategy and stick to it throughout the game. Many of them choose to use the basic strategy as it is one of the most popular methods around the world. Moreover, all it takes to apply it during the game is to memorise its patters and moves.

Another extremely famous approach is the card counting one due to the fact that it has proven to be very effective throughout the years. Both strategies have their pros and cons and it is entirely up to the players’ preferences to decide which one suits them best.

However, it is worth mentioning that in order to apply the card counting one successfully, players need to be familiar with the basic strategy principles as this helps them understand the patterns of the game better as well as the logic behind it.

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What is Card Counting

Card counting is a strategy which allows players to predict to some extent whether the next card will be beneficial for them or not. As the name hints, its fundamental principle is based on following all of the cards on the table in order to determine the likelihood of getting a particular one.

In general, card counting is considered to be a strategy used by more advanced players as it requires more concentration and analytical skills. Its main objective is to allow them to change the built-in advantage of the casino in their favour by keeping track of the cards.

This way players have the chance to decrease the amount of their money losses to minimum by increasing their wager only on the condition that the upcoming cards will be favourable for them.

A particular deck is in favour of the players when there are more power cards (A, K, Q, J, 10) than weak ones (2 through 6). The reason why is that if they know that the high-value cards are predominant, this hints to them that whenever they hit, the chances that they can get such a card are higher.

Thus, they can make better decisions about what their best move is and adjust their bets and strategy plays accordingly. For instance, they can choose to hit even if they have breaking hands provided that the deck is richer in low-value cards as this won’t cause them to go bust.

Cards Are Not Created Equal in Blackjack

No other casino game matches blackjack in terms of being exploitable. It all comes down to two mathematical concepts, those of dependent and independent events. Most casino games, including staples like roulette and craps, revolve around independent trials, i.e. the odds reset after each wheel spin or dice roll.

The likelihood of a given outcome happening next is not influenced by what has occurred in the past. The outcomes’ probabilities remain the same no matter how many times you have spun the wheel or rolled the dice. No helpful or accurate information is to be gained from previous independent trials. Scouting for hot streaks in such games is pointless in the absence of predictability.

In the game of 21, however, consecutive hands are actually dependent trials, which is to say previous results can and do affect the probabilities of future outcomes. Once a given card is dealt on the felt, you cannot expect it to reappear before the dealer puts it back in the deck and reshuffles.

If a single-deck player is dealt two aces on the first round, immediately after the dealer has reshuffled, while two other players have gotten blackjacks, nobody is getting any naturals until the next shuffle since there are no more aces in play. In this example, the house has a huge edge against the three patrons who are at a correspondingly big disadvantage.

This is due to another peculiarity of blackjack and more specifically, the fact that not all cards are created equal. In the game of 21, we can distinguish between player-favourable cards (A, K, Q, J, 10), house-favourable cards (2, 3, 4, 5, 6), and neutral cards (7, 8, 9). The odds fluctuate between the house and its patrons, depending on what cards are dealt and the composition of the undealt deck or shoe.

The removal of each card has a different effect on the expectation of the house and its players as you can clearly see in the chart provided below (the estimates are taken from Peter Griffin’s great book The Theory of Blackjack: The Compleat Card Counter’s Guide to the Game of 21). This is a statistically sound fact, proven by countless computer simulations that involved millions of played hands under specific rulesets as benchmarks.

Card Removal Effect in Single-Deck Blackjack Games
Denomination of Removed Card Effect of Removal in %
2 0.38%
3 0.44%
4 0.55%
5 0.69%
6 0.46%
7 0.28%
8 0.00%
9 -0.18%
K, Q, J, 10 -0.51%
Ace 0.61%

Here is how the simulations work. They take out a 3 from the deck, for example, and calculate the expected value of the basic strategy player when this particular card denomination is missing from the pack. The computations are then repeated with another removed card, say, an ace and so on. The casino’s advantage is then compared for each missing card to determine what effect its removal has on the players’ expected losses and profits.

If you pull out a deuce from a single deck, the absence of this card would boost the players’ expectation by 0.38%. Remove a Queen from a freshly reshuffled pack, and your expectation will drop by 0.51%. Provided that a deuce is dealt next to a ten-value card, then players’ negative expected value would be equal to (-0.51) + (+0.38) = -0.13%.

As is obvious from the chart from above, high cards like Q, J, K, A, and 10 favour the players, boosting their expectation. Respectively, their removal causes the player’s advantage to drop. Low-value cards like the deuce work to the advantage of the dealer, so their removal increases your advantage.

If you are tracking the ratio of low to high cards, you should press your bets when you have the edge and bet less or sit it out when the advantage swings back in favour of the dealer. Many different card counting systems effectively account for the strength of different card denominations.

Before we proceed any further, we would also like to specify that the cards’ removal effect decreases the more decks you add to the game. This is because the effect of dealing any given card becomes diluted. The effect of the card’s absence on the players’ gains or losses diminishes.

Low Cards Help the Dealer, High Cards Help the Player but Why?

If you are serious about playing blackjack at an advantage, it is essential for you to understand why exactly the excess of high cards harms the dealer and why prevalent low cards harm the player. Both answers have to do with the basic rules of the game.

The dealer is bound by house rules to hit hard totals 12 through 16 until they either bust or arrive at their standing total of 17 or above. The dealer is in trouble whenever there are more ten-value cards to be dealt because drawing one such card would cause them to break these hard hands. The opposite is true when low cards dominate the deck – the dealer is more likely to draw to a good total without the risk of breaking.

There are several reasons why the prevalence of high cards is helpful to the player. First off, the player stands better chances of receiving blackjacks with this deck composition. Of course, the same is valid for the dealer. The difference is that unlike the dealer who collects even money for their blackjacks, the player receives a bonus payout of one and a half times their winning bet (3 to 2) when they have a natural.

Then again, the player will see more successful double downs during ten-rich decks since there are more high cards to give them solid hands with a single hit. Doubling normally occurs against weak low cards of the dealer. The chances of the dealer busting when starting with a low card increase further whenever high cards outnumber low cards.

These tendencies are to be observed with pair splitting as well. The splits of pairs like 8-8, 9-9, or 7-7 become more profitable for the player on occasion the deck is richer in high cards. Another benefit of card counting results from the fact insurance becomes a good bet when more tens and aces remain to be dealt.

The chances of the dealer flipping over a card to complete a blackjack increase the more high cards remain unplayed. By contrast, basic strategy players never take the insurance bet because they have no knowledge of the deck’s current composition. Insurance has a huge house edge with a neutral deck or shoe.

The Essentials of Card Counting

The premise of card counting is not difficult to understand. You track the cards as they are dealt to gain knowledge of the changing composition of the deck or shoe. Bets are increased only when there are more unplayed tens as this is when the edge swings in favour of the player. Whenever there are more small cards to be dealt, the house regains its advantage.

The player would either bet the table minimum or not bet at all, a technique known as “wonging out” after expert Stanford Wong, who came up with it. So far, so good. The trouble is mastering card counting requires a decent amount of time, patience, and practice. Additionally, there are several other aspects you need to master to become a winning card counter.

Basic Strategy and Playing Deviations

You must commit perfect basic strategy to memory before you even begin to think about learning to count cards. This venture would be completely useless without basic strategy (BS). There are several reasons for this. To begin with, between 60% and 80% of counters’ advantage results from the use of basic strategy.

You can gain an edge even if you are betting in correlation with your advantage and use BS. Furthermore, you need to use BS after the reshuffle until enough cards are dealt to significantly change the deck/shoe composition. The remaining 20% to 40% of card counters’ advantage results from their use of playing deviations, also known as indices.

Indices denote the times when players must deviate from BS because the composition of the deck or shoe justifies it. One great example of a playing deviation is to take the insurance bet whenever the True Count rises to +3 or above.

Similarly, on neutral or positive counts, i.e. 0 or higher, a hard 16 versus a 10 is no longer a hit or a surrender. It becomes a stand for advantage players. There are many different indices but novice card counters are generally recommended to start with Donald Schlesinger’s Illustrious 18. This blackjack expert researched many different playing deviations in the 1980s and established these 18 indices boast the highest profitability.

Also important is to learn the Fabulous 4, which comprises four indices for the surrender play. One example is the hard 14 versus 10 index. As we hope you have learned from this guide, this hand is a hit versus a 10 with basic strategy in shoe-dealt blackjack. However, this hard total becomes a surrender against the 10 whenever the true count rises to 3 or goes above.

If you are keen on math and want to gain a more profound understanding of blackjack advantage play, we recommend you to check out Mr. Schlesinger’s book Blackjack Attack: Playing the Pros’ Way. There, you will find all the Illustrious 18 and Fab 4 indices along with tons of useful information on team play, spreading your bets, camouflage play, and analysis of players’ risk. A little more information on playing deviations is also available in our article here.

Choosing a System and Assigning Tags to Dealt Cards

Once you have learned perfect basic strategy, you need to pick the card counting system that best suits your style and goals. There are many different systems, each one with different levels of complexity and efficiency. The numerical tags assigned to high, low, and neutral cards also differ across systems. The Speed Count and the Ace-Five Count are two of the easiest systems to learn and implement. They are recommended for novice counters.

Rookies should steer clear of highly complex systems like Wong Halves. Using them is likely to result in too many playing errors, which, in turn, leads to a drop in the system’s efficiency. Mistakes can completely cancel out the slightly higher edge complex systems yield.

Most counters prefer to use the Hi-Lo system because of its relative simplicity and decent enough level of efficiency. The system has been proven as effective by many professional players and teams, including The Church Team (active years 2005 – 2011) and the MIT Blackjack Team (1979 – 1993). These professionals have extracted millions of dollars in gains from the casinos’ coffers by using the Hi-Lo.

Players who utilize the Hi-Lo count assign the following numerical tags to the cards: 2 through 6 = +1, 7 through 9 = 0, and 10, K, Q, J, and A = -1. Your goal is to add or subtract these values after every dealt card to keep what is known as the Running Count (RC).

Here is an example of how the Hi-Lo works. Three players are sitting at a blackjack table. Player A is dealt 3-A, Player B receives Q-Q, and Player C gets 8-2. The dealer shows a 5. It follows you have a Running Count of zero since 3-A is 0, Q-Q is -2, 8-2 is +1 for a -1, and the 5 is another +1 for 0. With Hi-Lo, the player begins to gain an advantage at a True Count (TC) of +1. The edge percentage increases by half a percent for every +1 added to the TC.

Running to True Count Conversion

Back in the 1960s and 1970s, keeping a Running Count like in the example above would have been sufficient to give you an edge since all blackjack tables used single decks. The trouble was that casinos quickly wised up after Edward Thorp published his now-iconic book Beat the Dealer, where he introduced the notion of card counting.

Casinos got scared (and for a good reason) so they decided to introduce multiple decks into play in hopes of hindering advantage players. The good news is this did nothing to prevent skilled patrons from exploiting their blackjack games.

Players can still gain a decent edge in multiple-deck blackjack as long as they convert their Running Count (RC) into a True Count (TC). The True Count is the count per undealt deck. The conversion to True Count involves dividing your current Running Count by the number of decks that are still in play, i.e. TC = RC / RD where RD stands for “remaining decks”.

One example of this is when you have an RC of +2 in a six-deck game and you see 2 decks in the discard tray and 4 decks in the shoe. Thus, you have a TC of 2 / 4 = 0.5, which is to say are yet to overcome the house edge and press your bets.

Deck Estimation

To convert your Running Count into a True Count accurately, you need to learn deck estimation, i.e. determining correctly how many decks have been played and how many remain to be dealt. You will be surprised to find this is easier said than done, though. Nonetheless, you need accuracy in this respect to count cards successfully.

There are different approaches to learning deck estimation. Similarly to choosing a counting system, you should again go for the approach that works best for you. Some novice counters prefer to divide by the nearest full pack to avoid complex calculations.

However, players who are looking for greater accuracy (which translates into greater advantage) can upgrade to dividing by the nearest half pack. This would add approximately 5% to your expected value compared to dividing by the nearest full pack.

As for drills on deck estimation, all it takes is practice although a sharp eye would also help. One commonly implemented approach is to buy many decks and divide them into stacks of 1, 1.5, 2, 2.5, 3 decks, etc. You can keep the cards in place by tying your stacks with rubber bands.

Contemplate the different stacks up-close consistently until you can remember and visualise what each number of decks looks like. Indeed, you will have to work your tail off as this is a cumbersome task that requires patience. Nonetheless, you cannot count cards in shoe-dealt blackjack without proper deck estimation and accurate RC-to-TC conversion.

Bet Spreads

Once you learn to count cards perfectly, you must pick a betting spread so you can size your wagers in proportion to your advantage. Counting cards is completely pointless if the player does not adjust their wagers in relation to the True Count. There is no uniform bet spread that suits all players. The choice of a betting ramp is based on many factors including your personal level of comfort, your chosen casino’s level of tolerance, your bankroll, and so on.

Table limits also should be taken into account. A player with lower risk-tolerance might prefer to spread their wagers from £10 to £100, for example, whereas a person with a bigger bankroll and higher risk-tolerance might be comfortable with a betting range from £10 to £200.

The bottom line is you need to move your wagers with the increasing or decreasing TC. Also needed is to determine the highest ceiling for the True Count, i.e. how high you expect the TC to go during a given playing session. For instance, if you determine a TC of +10 for a spread of £10 to £100, you will have to bet in multiples of £10 and increase your wagers proportionately.

Here is an example: Negative or Neutral TC = £10, TC of +1 = £10, TC of +2 = £20, TC of +3 = £30, and so on until you reach a TC of +10 and press to the maximum of £100. Note that this was only a straightforward example for simplicity’s sake. Such high counts are a rare occurrence in multiple-deck games.

Advantages of Card Counting

One of the biggest advantages of the card counting strategy is that players can completely overturn the house edge and gain a long-term advantage. However, it should be noted that this can be only done provided that they are excellent card counters and have acquired the needed concentration and discipline.

Players can also greatly benefit from it due to the fact that it gives them the chance to turn a long-term profit as they have the power to alter their bets in accordance with the remaining cards in the deck.

The concept that card counting can be learned only by people with good mathematical skills is wrong and it serves as a good excuse for gamblers who are not willing to put enough effort and time into learning it.

What it really takes to master it is a lot of practice and dedication. In terms of the mathematical part, it is worth mentioning that all calculations are very basic and they shouldn’t be an obstacle if you are good at fourth-grade math.

Disadvantages of Card Counting

One drawback of this strategy is that it requires a high level of concentration and it can be really hard for players to achieve it in a casino. They should be prepared to encounter a lot of distractions around them and therefore, should be disciplined enough to resist any temptations that may draw their attention in order to stay focused.

Counting errors are costly so the best course of action is to practice at home with distractions before you are casino-ready. Turn on the volume of your TV loudly enough and ask some of your friends to join you in training to recreate the distracting atmosphere of the casino floor.

Card counting allows players to alter their decisions accordingly and take advantage of the information the cards give them. However, this can be a double-edged sword. The reason why is that making a decision at the moment might be influenced by other factors such as feelings or the background. Thus, in such moments, discipline plays a crucial role and shouldn’t be underestimated in any case.

Perhaps, the biggest disadvantage of card counting is that many casinos are reluctant to have players who practise it as it gives them a huge advantage if applied correctly. This is the reason why they should be extra cautious and be careful not to draw much attention to their moves and bets. Many professional card counters manage to avoid detection by using camouflage techniques to outwit the floor personnel.

Finally, there is the problem with finding decent enough playing conditions that will allow you to gain a sufficient edge. An increasing number of terrestrial casinos are beginning to offer poorer rules to thwart advantage players. They either impose lousy rule restrictions, use Continuous Shuffling Machines or instruct their dealer to reshuffle at random and give players bad penetration.

Important Things to Consider Before Using Card Counting

Prior to using the card counting strategy, players should take into account a few important things. One of them is the number of decks involved in the game. This is really essential as the strategy’s main principle is based on the probability of what cards might come along next.

It is also worth mentioning that even though players need to be extremely concentrated and follow every card, this doesn’t mean they should remember every single one of them.

What they should really look for is the ratio of strong and weak cards. The reason why is that this is a good indicator for them whether they have a chance of drawing a high-value card or a low-value one.

Respectively, in most cases if the shoe is likely to be rich in power cards, it works in favour of the players. Another very important thing they need to consider is that before they start practising card counting, it is recommended to master the basic strategy first.

The reason why is that the card counting works best if combined with the basic strategy as even if players become perfect card counters, they won’t be able to achieve the desired win if they lack basic knowledge of the game.


Card counting is a strategy that allows players to draw conclusions based on the remaining cards in the shoe whether or not they are in a favourable position. It is practised by many proficient players who know that it can give them a huge advantage over the casino.

To apply it correctly, it is best to be familiar with the basic strategy and its patterns. The only way to achieve the desired result is to know the strategy backwards and forwards and use it throughout the game.

Combining both strategies give players the valuable opportunity to win, using their skills and knowledge. This is the reason why Blackjack is one of the most popular games all over the world and it is played by millions of gamblers.