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How do Online Casinos Prevent Card Counting?

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Rudie Venter
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Card counting, while not illegal, is frowned upon at casinos and has been used as a reason to ban players from returning. Card counting involves keeping tabs on the cards drawn and using that knowledge to predict what remains in the deck. More often than not, blackjack is the game of choice for card counters, particularly those games where just a single deck is in play. However, card counting is not as prevalent in the online casino world as it is in brick-and-mortar casinos. Even so, casinos do take measures to ensure that you’re unlikely to prosper when counting cards.

What is Card Counting, and How Does It Work?

Card counting is a talent. In effect, it involves making mental notes on which cards appear on the table. You will then keep a rough estimate of the cards that have come up, and this allows you to guestimate which cards remain in the deck. Naturally, the more decks there are in play, the less likely you are to be accurate. Furthermore, shuffling the deck will effectively reset your count, making it near-impossible to predict what will land next.

Because the player’s odds are decent and because you can get away with very few decks being used, blackjack is a card counter’s game of choice. The player begins by assigning a value to each card, and that will help them keep a “running count” based on the values they’ve chosen with the cards dealt. This information can then be used to calculate the count, creating what is known as a “true count”. Your bets will then rise (or fall) based on that count. This sounds complicated. However, to better explain what we mean, let’s look at a basic card-counting technique known as the Hi-Lo:

  • Cards 2-6 are valued at +1. Cards 7-9 at 0 and 10s through Aces are valued at -1.
  • As a new card lands, you will add one, subtract one or do nothing to your running count. The higher the running count is, the more advantageous it is for you to bet. If the count runs into the negatives, the casino has the edge.

To get around this, casinos started using multiple decks. This is where the “true count” comes in. To figure that out, you need to divide the running count by the number of decks remaining. For instance:

  • If we have a running count of 10 and an estimated five decks left, we divide ten by five to get a true count of two. 
  • Alternatively, if we have a running count of -7 and just two decks left, the true count becomes -3.

You can then use the true count number to gauge whether the edge lies with you or the casino.

Deck Penetration Explained

Deck penetration is another aspect of card counting worth learning. Each game will see dealers (human or AI) go “so far” into a shoe before they decide to shuffle it. The standard is around five decks, but that can change. Ultimately, the more cards a dealer burns through before shuffling the deck (the greater deck penetration), the easier it is to make use of card counting. Low deck penetration ensures that the dealer will never use too many decks before shuffling, thus making things harder for card counters.

Can You Count Cards in Online Blackjack?

This brings us to online blackjack. Card counting is a lot easier in physical blackjack games, predominantly at land-based casinos. However, while those venues represent your best shot at card counting, they aren’t the only way to count cards. Counting cards in online blackjack is “sometimes” possible, and here’s how:

Regular Blackjack

In regular blackjack games (known as RNG blackjack games, on account of the random number generator algorithms used), the deck is shuffled frequently, sometimes before every hand. Single-deck blackjack games give you a decent shot at card counting if the decks aren’t shuffled regularly, but this is rare. These games aren’t card-counting friendly.

Live Dealer Blackjack

Live blackjack, on the other hand, may open a window for card counters. The game is played with a real human dealer, and therefore, the dealer is subject to the same mistakes any human can make – something you won’t get with AI dealers. There does tend to be more shuffling by live dealers than a dealer in a brick-and-mortar casino, so card counting doesn’t quite have the same effect. However, it is worth trying because the dealer may forget to shuffle the deck and make mistakes.

Is Online Blackjack Beatable?

You can land wins in blackjack, so the game is beatable. However, don’t expect to land wins all the time. There is no cheat sheet or strategy guide that guarantees success over the dealer, even when counting cards. However, by using the Basic Blackjack Strategy, you can certainly improve your game. Basic Strategy is a chart that tells you the best moves based on the cards on the table. It isn’t a guaranteed pathway to success, but it will improve your game, especially when used alongside card counting.

Main Ways Online Casinos Discourage Card Counting?

Casinos naturally aren’t fans of card counting. They don’t always have much luck in banning players who count cards, as doing so isn’t illegal. As card counters have become smarter and newer techniques have been developed, online casinos have had to become equally as adept at tackling the issue. There are various ways that they currently do that, including: 

  • blackjack rules

    Deck Shuffling

    Casinos incorporated the use of multiple decks in a bid to thwart card counters. The creation of the true count gives card counters some of the edge back. However, calculating a true count is less reliable than a running count with just a single deck, so it's not a perfect system by any means. Therefore, deck shuffling helps the casinos in the long run. When they aren’t using multiple decks, they are choosing to shuffle just a single deck over and over between each hand. This effectively resets your running count, making card counting near impossible.

  • fairness of terms and conditions

    Software Monitoring

    Modern-day casino software uses AI and algorithms that make it easier for the games to track card counters. By using a player’s betting patterns, the AI can guess if the player is counting cards. It isn’t a fool proof way to protect against card counters, but it does give the casino a heads-up. However, there isn’t a whole lot the casino can do to the player at that moment. As mentioned, card counting isn’t illegal.

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    Low Rounds Per Hour

    Casinos do have one trick up their sleeve, which is particularly effective. They slow down the rate at which blackjack hands are played. Keeping a running and true count works better when the game is played rapidly. Human dealers are more likely to make mistakes under pressure. By slowing down the game and playing fewer hands per hour, card counting becomes much more difficult.


There are definitely games out there where counting cards is possible, even if only for a limited time. That, coupled with Basic Blackjack Strategy, can prove to be a powerful technique to improve your game and boost your chances of success. There’s no sure way to bag wins every time when playing blackjack, though, and trying to do so online is even trickier than pulling off the feat in brick-and-mortar casinos.

Rudie Venter

Rudie VenterVerified

Senior Content Writer

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Rudie Venter is a seasoned iGaming expert with eight years of industry experience. Holding a degree in Psychology, he combines academic insight with practical knowledge to offer expert advice on real money online casinos and how to gamble responsibly. Rudie's commitment to ethical standards ensures that his recommendations are trustworthy and informed. On his time off, Rudie loves a good old braai and watching the rugby with a naughty Klippies & Coke (in moderation of course).

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