Is Card Counting Illegal at Casinos?

Every casino has a house edge in almost all their casino games. Whether it's spinning roulette wheels, craps, or rolling dice, the Irish casino is assured that they will get the better end of the profit. However, in a blackjack game, players can tip the odds in their favour by learning how to play the game, deploying the strategy, and counting cards. 

In this casino guide, we will explain what card counting is, how to do it, reasons not to do it, and its legal implications in gambling.

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This page is written by
Seánie O'Brien
Seánie O'BrienCasino Adviser
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Rebecca Mackay
Rebecca MackayHead of Content

Card counting often evokes the notion of a strategy that could result in a permanent casino ban for individuals. However, is card counting truly illegal? In this informative video, as your host I will address this query and delves into a range of topics, including comprehending card counting tactics and the methods employed by casinos to detect and prevent such practices.

What is Card Counting? The Theory

A suave man sits in a suit at the blackjack game table. His admirers look on in anticipation to see the final deciding hand. The other players have stoic looks because they know they will lose. The hand is revealed, and the table erupts in joy. This is a casino scene from almost every action movie in Hollywood - and it is always revealed that the protagonist was using a card counting system to his advantage to beat the odds. And this is where the card counting fever comes from.

Anyone can count cards if they learn how to do it right. It is a relatively simple playing strategy that relies on accuracy and concentration. The only thing you need is an alert and present brain. 

In a game of blackjack played with a single deck of cards, the house edge is almost zero if you play using the optimal method. You will eventually break even. The odds of winning blackjack are high, and it is these odds that make the game perfect for card counting. 

What is card counting

Card counting means keeping track of specific cards when the dealer plays through the deck. You do everything else as normal - play with the best strategy - and you will know which cards will come up for you and the dealer when the next hand gets dealt. 

When you have an insight into these odds, you can decide more easily when to bet, big or small. If you have more low-numbered cards left on the deck, you might be out of luck because your chances of getting a blackjack are low. The dealer is also less likely to get a bust, which is getting over 21 points worth of cards, because of the rigid betting rules. High-numbered cards are most desirable. 

If you count cards correctly, you can likely increase your odds of winning by 1%. While that doesn't sound like much, it's a tried and tested way of doubling your bankroll by winning more money at the games. 

Quick Facts About Card Counting

In a rush? Check out the list below for a summary of what you'll find in this article about card counting:

  1. The media has made card counting popular amongst blackjack players, especially in movies based on gambling or heists requiring a high cash input. 
  2. You must master the blackjack strategy before learning to count cards. 
  3. When you count cards, you keep a tally of specific cards the dealer plays through the deck. You can do this by tracking high-numbered, middle-numbered, and low-numbered cards. Once you have that in mind, you have an idea of which card will come up next for you and the dealer, and you can place your bet accordingly. 
  4. The easiest strategy to master is hi-lo. 
  5. Casinos would like you to believe that you are committing a crime. However, you are not doing anything against the law. Card counting is perfectly legal. However, casinos reserve the right to stop you from playing and barring entry for you in the future.
  6. Casinos use CSMs, multiple decks, RFID technology, security surveillance and body language 'tells' to catch people counting cards.
  7. Card counting isn't as glamorous as movies make it out to be; profit margins are thin, you need a lot of money to begin, and it isn't that fun.

The Easiest Strategy

The hi-lo or High-Low system is one of the easiest ways to count cards at the blackjack table. With this strategy, the card counter only has to keep track of three groups of cards: the high numbers, the low numbers, and the middle numbers. This is how it works:

  • For every high-number card the counter sees played on the table (the 10s and all the face cards), he/she will subtract one from his/her tally. 
  • The middle cards - sevens, eights, and nines - are ignored. 
  • For every low-number card - the sixes to the twos - he/she will add one to his/her tracking record.

For example, if the running tally is more than three, the cards coming up are likely to be high-numbered, so it's in your favour to place a high bet. On the other hand, if the tally is less than two, the odds are in the dealer's favour because you are likely to get low-numbered cards - so you should place small bets. You reset the count and start again when the cards get shuffled. 

It sounds like a lot, but running a count can be quite easy once you get the hang of the steps. Card counters need a lot of practice, so you must play several rounds with a team before you practise it at the casino. You simply need to keep your eye on the card's value and the game's goal. But you can expect to make mistakes when you initially get into it. 

Counting cards is a long-term strategy, and to build up your 1% edge, you need to play by the optimal method, round after round. Simultaneously you must keep track of the ratio of the cards being dealt and flipped on the table.

Tips and Tricks for Master Card Counting

  • It is very important to keep your focus. stay away from trivial things like alcohol and pay little attention to the comings and goings of a bustling casino. 
  • Start with smaller stakes. You should only risk a small amount while playing when you are a beginner, like €5. Once you have the hang of the strategy, you can migrate to higher stakes. 
  • Keep a close eye on your bankroll. You can expect losses just as much as you can expect wins. Make sure that you have a bankroll that supports you.
  • Hide your ability to count cards. There are cameras all around, and eyes will be glued to you if you play long games at the tables for hours without taking any breaks. You must blend in - dress like a tourist, and don't show up in a suit trying to emulate Brad Pitt! 

The Problems with Card Counting

Contrary to what most people believe, the truth is that card counting is not illegal. Most casinos would like you to believe it is, but it's not. It is not even considered cheating - the player is simply thinking one step ahead of the pit boss or dealer. You play the game exactly as the casino offers it. You're simply better than everyone else.

Card counting is not illegal under the laws of Ireland. No law states that casino goers cannot count cards. If you're playing blackjack at an online casino based in the US, you should also be aware that no federal, state or local laws ban card counting - unless you are using some type of external card counting device or have people helping you with your card count. 

Keep this information at the forefront of your mind should you ever get caught. It is important to know your rights - the police cannot arrest you for counting cards or convict you of any crime. However, casinos reserve the right to ask you to stop playing. Some casinos will immediately eject you from the premises and prevent you from redeeming your chips with the cashier. Sometimes, the casino might even ban you from playing with them again. 

However, casinos have a good reason to stop card counters - they want to protect their house edge and know that card counters can and will cost them money. 

Card Counting

Ways Casinos Can Catch and Prevent Card Counting

There are five main ways a casino catches or prevents card counting:

1. Multiple decks 

For blackjack games, casinos may use three or even four decks to prevent card counting. The higher the number of cards in play, the harder it will be for card counters to keep track of the cards.

2. CSM

Also known as continuous shuffling machines, CSMs allow dealers to place the dealt cards into the shuffling machines for reshuffling. The reshuffling of cards minimises deck penetration by a large margin, making it nearly impossible for players to count cards. This is because there is no lull or pause in the game. Zero pauses or lulls can confuse the players and shift their focus even if they keep trying to assign values to the cards in play. 

3. Security Surveillance

Casinos have high security - for obvious reasons. They have a target on their back because of the sheer volume of cash they handle within the premises. Hence, casinos have numerous security surveillance cameras installed. The cameras are mounted tactfully, and out of sight, so players aren't even aware of being watched. 

The cameras help the casino management keep a close eye on the casino floor and the players to catch any possible cheating or tampering activities that could be taking place. Furthermore, card counters can be caught by their body language and other cues that the staff is trained to keep an eye out for.

4. Body Language and Dress

Telltale card counters are people who

  • Hyper-focus on the game
  • Bet amounts of money that vary wildly between high bets and low bets
  • Bet seemingly randomly
  • Play for long periods without taking a break from the table
  • Don't make small talk

5. RFID Chips 

Casinos use RFID technology to ascertain what the player has bet. The technology is integrated into the chips, and the sensors get placed under each table. The RFID chips allow the casino to find the average bet rating accurately. With real-time betting data in their hand, casinos have a clear idea of the various betting patterns of the player. If the patterns are too well-calculated and identical, it arouses suspicion and flags the card counter to the staff. 

The Case Against Card Counting

Games like 21, based on the MIT Blackjack team, have inspired many people to take up card counting at some point in their lives. But movies don't capture the entire picture.

Here are three reasons why you shouldn't card count:

1. Thin Profit Margins

Despite what movies tell you, card counting only gives you a small edge over the casino. If you're expecting to win millions on your first try, prepare to be disappointed. Most players win money slowly, winning a couple of thousand on their best night.

2. It's Not Exactly Fun

For many people, the point of going to the casino is to have fun and enjoy the thrill and adrenaline of possibilities. Card counting is the opposite of fun. It can be tedious and suck the fun out of casino games. It requires a special amount of focus and commitment - a lot of brain work which is the opposite of shutting down your brain after a long day.  

3. You Need Money

Profits are only partially guaranteed with card counting. While you will be shifting the house advantage in your direction while playing cards, you probably won't start winning the game straight away. Instead, it will take some time to make a profit. This means that you have to start with a heavy bankroll. 

Do you know how much the MIT Blackjack team started with? $89,000!

Our Verdict on Card Counting

To sum up, while card counting may not be illegal, it is frowned upon by casinos, and individuals caught engaging in it may be subject to various repercussions. These could range from being banned from the casino to facing legal action. Therefore, weighing the potential risks and rewards before attempting card counting in a casino setting is crucial.


Is card counting illegal?

No, card counting is not illegal in most places simply because it's a strategy that keeps players one step ahead of the dealer in the game. It is perfectly legal in Ireland and countries like the UK and Canada.  

Is card counting risky?

Yes, it is slightly risky because casinos can ban any player caught counting cards. Card counting endangers the house's edge and impacts profits.  

How can I avoid getting caught?

Dress casually. Make small talk. Vary bets minimally. Don't play at one table for too long.

Casino Mentor

Seánie has plenty of experience in the casino world and enjoys sharing this accumulated knowledge. He offers great tips and tricks for players to enjoy casinos safely.

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