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How Do Casinos Know If You Are Counting Cards?

How Do Casinos Know If You Are Counting Cards?

Card counting, a widely known strategy used in the gambling world, specifically in blackjack, has been a topic of contention for many years. While its legality isn't disputed universally, casinos worldwide view it as an unfair advantage and employ various measures to detect and counteract this practice. Let's delve into the world of card counting, how it's detected, and the measures casinos employ to prevent it. 

What Is Card Counting?

Card counting is a technique that involves keeping track of the ratio of high to low cards left in a deck. The player uses this information to make strategic betting and playing decisions, such as whether to hit, stand, double down, or split their hand, thereby gaining a potential advantage over the house. However, mastering this technique requires a high level of concentration, quick calculations, and significant practice. 

How Is Card Counting Detected?

Casinos utilise a range of techniques to spot card counters. Awareness of these techniques is vital to understanding how casinos are always one step ahead of card counters. 

Casinos monitor the behaviour of players closely, looking for patterns associated with card counting. This could include varying bet sizes, an overt focus on the game devoid of typical social engagement, or variations in play strategy, which can all red flag a player. Some casinos even hire expert card counters to observe players and identify potential card-counting strategies. 

Modern casinos employ advanced surveillance systems to monitor players' behaviour. Some even use facial recognition technology to identify known card counters. 

Will A Casino Kick You Out For Card Counting?

While card counting is not considered illegal in many jurisdictions, casinos view it as an unfair advantage. If a player is found to be counting cards, they could face repercussions ranging from a request to leave the casino to a permanent ban. However, casinos cannot legally confiscate a player's winnings unless they can prove the player cheated. 

How Do Casinos Stop Card Counters?

Casinos employ various measures to prevent card counting, both in physical casinos and online platforms. These measures vary in their effectiveness, but they all aim to disrupt the card-counting process and make it more difficult for players to gain an unfair advantage. 

Regular Deck Shuffling

Frequent shuffling of cards can disrupt the rhythm of card counters. Continuous shuffling machines (CSMs) are particularly effective as they shuffle cards after each round, making card counting nearly impossible. 

Use of Multiple Decks

Casinos often use multiple decks of cards in games prone to card counting, such as blackjack. This makes it harder for card counters to keep track of the cards and reduces the effectiveness of their counting strategies. 

Changing Betting Patterns

Card counters adjust their bets as they track the cards to account for getting a strong hand or a weak hand. Casinos may limit the range of bet sizes, making it harder for card counters to adjust their bets based on the count. 

Can You Count Cards At Online Casinos?

While card counting is possible in live blackjack games at online casinos, it is almost impossible in automated online blackjack games. This is because the deck is reshuffled after every hand, making it impossible for card counters to track the cards. 

However, even in live blackjack games, a multi-deck shoe is used, and another is shuffled while the game is ongoing, making it incredibly difficult to keep track of the shuffle and the game. 

How Do Online Casinos Prevent Card Counting?

Online casinos use largely the same methods as land-based casinos to prevent card counting. They adapt by integrating continuous shuffle mechanisms and using an RNG that mimics the unpredictability of a live game environment and allows for shuffling after every hand. Many online blackjack games use multiple decks and do not fully use one deck before switching to another, making card counting difficult. 

Similar to physical casinos, online platforms also reserve the right to ban players suspected of card counting. Online casinos on the same network can also communicate with each other to identify a known card counter. 


In conclusion, card counting, while not illegal, is frowned upon by casinos and has led to various countermeasures designed to detect and deter card counters. As the landscape of gambling continues to evolve, card counters may find it increasingly difficult to practice their strategy, both online and in physical casinos.