Counting cards at Blackjack

Every game in the casino has something called a house edge which means that “the house always wins”  in the long run. Blackjack is the only casino game where the player can turn a house advantage into a player advantage through study and practice. The reason for this is that the player can keep track of what cards have been dealt and increase their bet when the deck has more favourable cards for the player. This is done through card counting and is perfectly legal although the casinos do have the right to stop you from playing if they catch you doing it. Rest assured though that most casino’s fully accept some people will card count and beat Blackjack because the majority of people will lose.

Assuming you know how to play Blackjack (See a beginners guide to Blackjack), before learning to count cards, you need to learn basic strategy which is the mathematically correct way to play each hand depending on your total compared to the dealers card. The chart below shows you the correct strategy as played with 6 decks which is what most casinos in the UK use. This needs to be memorised before starting to learn basic strategy.


Basic Strategy


Research carried out in the 1960’s by Edward Thorpe, a mathematics professor, led to the creation of a card counting system. This meant a player could keep track of which cards had been dealt thus knowing which cards are remaining  and enabling the house edge to be turned in favour of the player. This means a player can win consistently playing Blackjack. He discovered fundamentally that when more high value cards are remaining to be dealt that it is in the favour of the player as the dealer is more likely to bust because they have to follow set rules of when to draw and when to stand.

The high-low count which is described in the movie 21 with Kevin Spacey is the most common counting system and is very simple to learn. The cards with a face value 10 (10,J,Q,K,A) are all counted as -1 and the lower cards (2,3,4,5,6) are all assigned a value of +1. The middle cards (7,8,9) have a value of zero. For every card that is dealt you need to add or subtract one depending on what the face value is. For example if a 10, jack, 7 and Ace was dealt, the running count would be -3.

You keep track of this number in your head always adding or subtracting one. The last thing you do is divide this number which is the running count, by the number of decks remaining to be dealt to give you the true count. For example if you have a running count of +6 and there are still 3 decks left to be dealt then you do 6 divided by 3 which gives you a true count of +2.

The idea is to increase your bet when the count is high because that means there are a greater number of high cards in the deck which gives the player the advantage and decrease you bet when the true count is negative.

Top Tip

Card counting won’t work in online casinos because the shoe is reset after every hand. However it is a good place to practice counting cards before entering real world casinos.

There are different counting systems available apart from the high-low count. You can find out more in the book below.

Recommended Reading

Professional Blackjack – Card-counting advice for beginners to experts to enable consistent winning at Blackjack.

The World’s Greatest Blackjack Book – A comprehensive guide covering everything you need to know to win at Blackjack using the authors specially developed system.

Bringing down the House – The true story of a team of  MIT students who took Vegas for millions working in a team to count cards at Blackjack.

Sites to use

Grosvenor Casino – Practice playing Blackjack online with Grosvenor Casinos. Also get a sign up bonus when you are a member of their land based casinos.