Card Counting in Blackjack
Films such as 21 and The Last Casino have made card counting familiar to many people. It is most closely linked to blackjack, where players track the cards dealt to estimate whether those still to come may favour the player or dealer. The house usually has a strategic edge, but careful play can shift the odds in a player’s favour. Card counting is one method that may improve a player’s chances of finishing ahead, but it cannot guarantee a win.
How Card Counting Works
Blackjack may be dealt from one deck or several, depending on the game. As cards leave play during each hand, tracking selected cards can help you estimate what remains. Card counting involves keeping that tally as the dealer works through the shoe.
Card counting follows a few basic steps:
1. Assign a Value to Each Card
You do not need a photographic memory to count cards. Many players use a tagging system instead: assign each card a numerical value, then add to or subtract from a running total as cards appear on the table.
Hi-Lo is a popular and relatively straightforward counting system. Each card is assigned a value of -1, 1 or 0; across a single deck of 52 cards, the values add up to zero. The card groups are scored as follows:
- Cards 2-6: 1
- Cards 7-9: 0
- Cards 10-Ace: -1
2. Keep a Running Count
As each card is dealt, update the total by adding 1, subtracting 1 or leaving it unchanged according to its assigned value. Starting at zero, a queen brings the count to -1; if the next card is a 4, it returns to 0 (-1 plus 1 = 0). A higher running count suggests more high-value cards may remain in the deck.
3. Calculate a True Count
Casinos often deal blackjack with multiple decks. That makes the count harder to keep, but does not make the method useless. In a multi-deck game, convert the running count into a true count, also known as a count per deck, to account for the cards still in play.
Divide the running count by the estimated number of decks left to get the true count. For example, a running count of 10 with 5 decks remaining gives a true count of 2 (10 ÷ 5).
4. Adjust Your Bets Based on the True Count
As play moves through the shoe, the true count can rise or fall, and some counters adjust their wagers accordingly. They may bet more when the count rises and keep bets small when it is neutral or negative. Any betting decision should take the player’s bankroll into account too.
Is Card Counting Effective?
New players often wonder if card counting works. It depends on the game and the player’s skill: a capable counter can gain a modest edge over the casino, but not a large one. Experienced counters may gain an advantage of about 0.5% to 1%.
At online casinos, card counting is generally less useful than at a table, including a live dealer game. Online live casinos may make it difficult to track cards by dealing from 8 decks, shuffling automatically or burning cards at the start of the shoe. These measures can make an accurate count difficult or even impossible.
Consequences of Card Counting
Card counting is not currently illegal, but a casino may ban a player it suspects of counting. Casinos can also change table conditions by adjusting the minimum or maximum bet, placing the cut card earlier or using automatic shuffling machines. These steps reduce the usefulness and enjoyment of counting at that table. Rules and consequences vary by jurisdiction and venue.
Getting Started with Card Counting
Learning to count cards takes patience and regular practice. Exceptional intelligence is not needed, but players do need to think quickly and do mental arithmetic. With practice, counting may also help you become more familiar with blackjack decisions.
