Blackjack Card Counting – How it Works

Blackjack is the casino game with the smallest house edge. Using the optimal strategy, the house advantage can be reduced to less than 1%. Yet even with these favourable conditions, in the long run, the casino ultimately comes out on top. However, here is where card counting comes into play. Using this tactic, you can reduce the house edge as low as it can possibly go, and even make profits in the long run. In this page, I will show you how to count cards and show you where you really can make money.

How does it work in General?

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By counting cards, you get an overview of the balance of high and low cards which are still in the shoe. This enables you to assess whether the situation is better than average, meaning that you have a higher probability of making a profit. In this way, you can exploit the positive situation, by placing higher bets, which will compensate for any previous losses, and can also enable you to make additional profits. Therefore, card counting influences the amount of your bets. However, before using this tactic, you need to know the best moves to make for each situation. Therefore, you should use strategy tables to ensure that you to play each hand optimally to maximise your chances of winning.

So how do you identify these positive situations? How do you know when there are more favourable cards left in the shoe, meaning you should place higher bets in order to make bigger profits? You need there to be more high cards left in the shoe, like 10’s and aces, for a bigger chance of winning. This means that many small value cards need to be drawn towards the beginning of the game. The shoe usually contains between 4 – 8 decks of cards, and at the start of the game, there is the same probability for each card to be drawn. As the game progresses, you need to keep track of all the cards that are dealt. You do not need to remember each and every card that is drawn, you simply track the ratio of high cards that are dealt vs low cards. Therefore, when there are only a few cards left in the shoe, you will know whether there are a higher proportion of high cards or low cards left. At this point, if many smaller cards have been drawn, leaving more high valued cards, then you should increase your bet size.

The Running Count – How to Count the Cards

The simplest and most common way of counting cards is using the Hi-Lo system. This basic method assigns a positive, negative or neutral value to each card. All cards with a value of 2 to 6 count as +1, with all tens and aces worth -1. The 7, 8 and 9 are neutral as they do not particularly influence the overall outcome, so these count as 0. With a freshly shuffled deck, the count starts at zero, and for each card that is dealt (both to the players and the dealer) you update the running count accordingly.

Overview of How to Count Cards in Blackjack using the Hi-Lo System

Depending on the cards that are dealt throughout the games, sometimes the running count will be positive, other times it will be negative. For the best outcome, you need to end up with a high positive count towards the end of the card shoe. In this situation, you can increase your bet size, in order to maximise your profits. However, before doing so, you need to calculate the so called “true count”.

True Count Calculation – When to Start Betting Bigger

If you have a high positive running count, then your instinct may be to increase your bet size. However, there are more factors to consider before deciding whether you can exploit the situation. If your high positive count comes after just one or two games, this really does not give you a clear indication of which cards will be drawn next. This is because with so many cards left in the shoe, the variance is too high to accurately determine the probability of which cards will be drawn next. Likewise, if you get towards the end of the deck and have only a small positive count, say for example +2, this is also not conclusive enough for you to determine the next cards. Although the count is positive, there is very little difference to allow you to exploit the results to your advantage. For these reasons, as well as tallying the count of the card value, you also need to factor in the amount of cards that are left in the shoe. With both these pieces of information, you can calculate the true count. This result will enable you to more accurately determine which stakes you should play with.

True Count Calculation based on Estimated Remaining Decks
True Count Calculations Help Determine Which Stakes to Play With
The easiest way to calculate the true count is to divide the running count by the number of remaining decks in the shoe – then multiply by the total number of decks.
True Count Calculation based on Number of Remaining Cards
With a High True Count you should Increase your Bet
The same calculation also works with the number of remaining cards. But you have to keep count of the actual number of cards dealt in addition to the running count, and the calculation is more complicated.

The optimal way to play when counting cards is to start off by betting with the lowest possible table limits. If the true count gets higher, then you can increase your bet size accordingly.

Where the count is +1, zero, or even negative, you would continue to bet just the minimal possible amount. If the true count reaches far into negative figures, you should consider whether it is actually worth continuing to play. If the count clearly is not favourable towards you, it may be best waiting until the shoe is empty, or all cards are shuffled, and then start over again.

Optimised Card Counting Strategies

As already mentioned, this method is one of the easiest for counting cards, as all cards are assigned to certain categories. Rather than counting individual values, cards are grouped into positive, negative and neutral categories. However, clearly this generalisation of the card values does not provide the optimal way to count cards. For instance, an ace does not have the same value as a 10, likewise, a 2 does not have the same value as a 6. There are other systems which have evolved over the years that enable you to increase your expectancy of profits even further.

Yet with more precise systems, it becomes more difficult to count the cards, and it is not so quick and straightforward to master. There are even systems which do not use the true count calculation at all. The following table shows an overview of the various different systems, and how they work. This is for illustration purposes only; I will not go into details of each system here.

Strategy 2 3 4 5 6 7 8 9 10,J,D,K A Type Difficulty
Revere RAPC 2 3 3 4 3 2 0 -1 -3 -4 B4 1
Revere 14 Count 2 2 3 4 2 1 0 -2 -3 0 B4 1
Uston APC 1 2 2 3 2 2 1 -1 -3 0 B3 2,5
Wong Halves 0,5 1 1 1,5 1 0,5 0 -0,5 -1 -1 B3 2,5
Canfield Master 1 1 2 2 2 1 0 -1 -2 0 B2 4
Hi-Opt II 1 1 2 2 1 1 0 0 -2 0 B2 4
Mentor 1 2 2 2 2 1 0 -1 -2 -1 B2 4
Omega II 1 1 2 2 2 1 0 -1 -2 0 B2 4
Revere Point Count 1 2 2 2 2 1 0 0 -2 -2 B2 4
Zen Count 1 1 2 2 2 1 0 0 -2 -1 B2 4
Uston SS 2 2 2 3 2 1 0 -1 -2 -2 U3 4,5
Canfield Expert 0 1 1 1 1 1 0 -1 -1 0 B1 6
Hi-Lo 1 1 1 1 1 0 0 0 -1 -1 B1 6
Revere Adv. Plus Minus 1 1 1 1 1 0 0 -1 -1 0 B1 6
Silver Fox 1 1 1 1 1 1 0 -1 -1 -1 B1 6
Hi-Opt I 0 1 1 1 1 0 0 0 -1 0 B1 6,5
UBZ 2 1 2 2 2 2 1 0 0 -2 -1 U2 6,5
Uston Adv. Plus Minus 0 1 1 1 1 1 0 0 -1 -1 B1 6,5
KISS 2 0/1 1 1 1 1 0 0 0 -1 0 US1 7
KISS 3 0/1 1 1 1 1 1 0 0 -1 -1 US1 7
Red Seven 1 1 1 1 1 0/1 0 0 -1 -1 USC1 7
K-O 1 1 1 1 1 1 0 0 -1 -1 UC1 7,5
REKO 1 1 1 1 1 1 0 0 -1 -1 UC1 8

When does Blackjack Card Counting not Work?

From the various count types, you can already see how hard it is to make profits with card counting. This is because in different situations, with different rules, the strategies need to be adjusted very accurately. There are also games in which counting no longer works, primarily, when the cards are re-shuffled after each round. In land based casinos, this is a rare occurrence, even if there is an automatic shuffling machine in use. Whereas online, the entire shoe will be reshuffled within a fraction of a second, after every hand played. In this situation, counting the cards is no longer a possibility. One exception is live blackjack games, where real cards are used, meaning you can count the cards you see on your PC whilst playing from home.