Hobbies Card Games & Gambling How Blackjack Card Counting Works Share PINTEREST Email Print Christopher Furlong/Getty Images Card Games & Gambling Blackjack Gambling Strategies & Tips Casinos Sports Gambling Poker By Bill Burton Bill Burton has written about casinos and gambling since 2008. He is the author of two books about gambling and a monthly columnist for several national gambling publications. our editorial process Bill Burton Updated February 21, 2019 Blackjack is a game of skill and card counting can help you gain an advantage in the game. Edward R Thorp is considered the father of card counting. He discovered the principles of card counting and published his method in 1962 in his book Beat the Dealer. His writing started the Blackjack revolution, and it was also instrumental in the casinos taking action to ban card counters. Card counting is not illegal, but casinos can ban players from playing blackjack if they detect that a player is counting cards. Many people remember the movie Rain Main man where Dustin Hoffman’s character memorized all of the cards coming out of the shoe. This has given the wrong impression as to what card counting is. Even the term card counting is misleading because when you count cards, you are merely keeping track of the ratio of high to low cards left in the deck. Why It Works What makes blackjack different from any other casino game is that the house edge is not fixed. The odds of getting a natural blackjack are dependent upon the cards that have already been dealt and the cards remaining in the deck. If an ace is dealt on the first round the odds of drawing another ace has gone down. In the game of blackjack, your probability of winning a hand is dependent upon the mix of the cards remaining in the deck. If the combination of cards remaining in the deck contains high-value cards, it is a positive factor and is favorable for the player. When the deck contains a large number of tens and aces, it increases the players' chances of drawing a pat hand (17 or higher) or getting a natural blackjack. It also increases the chances that the dealer will bust. Even though the dealer is just as likely to draw a good hand when the deck is positive, the player is getting paid 3 to 2 for a natural blackjack. This is why card counters raise the size of their bets when the deck is rich with high cards. They may also deviate from basic strategy depending on the count. If the cards remaining in the deck are low-value cards, it is negative, and it favors the dealer. Card counters usually lower their bets when the count is negative. When the deck is rich in low cards it less likely that the dealer will make a pat hand and it also makes it less likely that the dealer will busts when he has to draw. Counting Methods The concept of counting cards is simple. Each rank of card is assigned a point value, and the card counter adds or subtracts those points to get a “running count” to determine if the deck is positive or negative. There are many different card counting systems used by the players. Some are more complex than others, but they all are designed to keep track of the high and low cards left in the deck. The values assigned to the cards determine whether a counting system is balanced or unbalanced. A balanced card counting method such as the popular Hi/Lo values a complete 52 card deck as zero. When you use a balanced counting system, you keep a running count of the cards as they are played, but you then have to divide running count by the number of decks not yet played to get the true count. With an unbalanced method such as Speed Count or Knock Out (KO) the total of the 52 card deck does not add up to zero. You start with a predetermined number to tell you when the deck is positive or negative instead of using zero as a starting point. The advantage of using an unbalanced method is that it is simpler because you don’t have to estimate the remaining decks and convert to the true count. Getting the Edge The purpose of any of the card counting methods is to tell the player when the deck is positive with high-value cards. The Blackjack player gains the edge over the house by betting more when the deck is positive and sometimes even deviating from basic strategy. The difference between the size of your bet when the deck is neutral or negative, and the amount you increase as it becomes positive is known as the spread. As the positive count increase so does your advantage. More Than Counting Being a successful card counter takes more than just being able to keep track of the cards. Many players find that they can successfully count a deck in the privacy of the quiet home but then have difficulty in a noisy casino with all of the distractions. Successful card counters must also be able to camouflage their play so they can go undetected by the casino pit bosses. The easiest way to get caught counting cards is to make big jumps in your bets from one hand to the next. You have to learn to play cat and mouse game with the casino, and if you can do that, you can get the advantage over the house. Be Realistic There are many players counting cards and making money, but you have to be realistic about your results. Card counting will only give you a one to two percent edge over the house, and the advantage you gain by card counting is based on the long run, and your given results during any single session can vary greatly. When the deck is positive, the dealer has just as likely a chance of getting the high cards as you do. Still, any edge you can gain over the casino is worth the effort that it takes to learn and to win is a lot more fun.