The Mechanics behind Card Counting at Blackjack

The Mechanics behind Card Counting at Blackjack

Although not illegal, the system of Card Counting in the game of blackjack is frowned upon by most casinos. This can see a player being banned from playing at their blackjack tables or even removed from the casino altogether. However it certainly is a good strategy for reducing the house advantage if you can play undetected. But how does it work?

The first thing most people think of when card counting in blackjack is mentioned is that it must rely on great memorisation techniques. This would mean that those of us with not great memories would not be able to consider learning this technique. Luckily though it is not based around having to learn how many Kings or two’s are being dealt.

When playing the game of blackjack the player has a better advantage when there are more ten value cards and Aces remaining (such as 10’s J’s, Q’s and K’s). This is because the player has a higher chance of being dealt a blackjack which has better odds of 2:1. There is also more chance of the dealer going over 21 and being bust. On the opposite side of the coin, with more smaller cards remaining there will be fewer blackjacks for the player and dealer has an increased chance of a good hand. So in principle the technique of card counting is just down to trying to keep track of the relation between high cards and low cards.

Assigning a Value to each Card

Here at Free Casino we are going to look at the Hi-Lo card counting strategy as it is the most common and widely used system. This system was first introduced by Harvey Dubner in 1963. This is the first step towards card counting where you allocate a new value to each of the cards as they are dealt. This is fairly straight forward as it it build around blocks/groups of cards.

The groups of cards and their value is as follows:

  • Cards with normal face value of 2, 3, 4, 5 and 6 have an allocated value of +1
  • Cards with a face value of 7, 8 and 9 have an allocated value of 0
  • Cards with a face value of 10, Jack, Queen, King or Ace are allocated a value of -1

As the cards are dealt by the dealer you will simply be adding 1 or subtracting 1 or doing nothing dependant on where those cards fall into the groups above.

Keeping a Running Count

So as the game progresses and for subsequent games until the cards are shuffled you will be updating the ‘running count’ as each card is dealt. This includes both player and dealer cards. If as you progress the running count is increasing then the advantage in the game is moving more towards the player. However the opposite is true if the running count decreases which means the advantage to the casino is increasing.


This system of card counting would mean if you were playing with a single deck then you could already start to manage your betting more effectively as you watch the way the advantage is going. Unfortunately casinos in their attempt to reduce the chances of card counters winning and beating the house introduced multiple decks.

Therefore if you are playing blackjack where multiple decks are in use you will need to also monitor the ‘True Count’ also know as the count per deck.

Calculating the True Count

If you were just playing with a single deck and had a running count of +5 it means there are at least 5 extra 10’s and Aces within the remaining cards. This would give approximately a 2% advantage to the player. If though your +5 running count was against a game with 6 decks still remaining then this would indicate less than 1 extra high card remaining per deck.

This is why the true count has to come into play. At any point in the game it will tell you what your advantage is in a blackjack game with multiple decks. To find out your true count you would simply divide your running count by how many decks are left to be dealt.

Therefore as an example if you had a running count of +10 with 5 decks remaining the true count would be 10 divided by 5 which would give a value of 2. If your running count was +9 with 3 decks remaining then 9/3 would give a value of 3. If you therefore combine the basic strategy alongside the Hi-Lo card counting system you can use the information to place your bets to your advantage and increase the chances of making that big win.

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