Card counting is a system that experienced blackjack players use to get a profitable advantage over the casino. There are many individual “counts” or systems. Many of them are named after colorful professional gamblers from times past.
The 2008 movie “21” bought card counting to the attention of the general public. It followed the true story of members of the MIT blackjack team as they won millions from casinos in Las Vegas. This movie also highlighted the key challenge faced by card counters. To make a profit using these systems, you need to bet significantly more when the odds turn in your favor. Casinos are aware of this — and will quickly ban players they believe are counting cards.
This page has everything you need to know to get started with card counting. Below you will find the basics of how it works. Famous systems, the ideal games for counters and how online blackjack can help you learn to count are also covered below.
How to count cards in blackjack
Blackjack is a game of incomplete information. Players act based on their own two cards and the single dealer up-card. Players must risk busting in many situations, even though the decisions are mathematically correct.
Small cards are the enemy of blackjack players. Values of two through six can make for the trickiest decisions. In fact, if you remove any significant number of small cards from the shoe, blackjack not only becomes easier, the player gets a mathematical edge over the house.
This is where card counting comes in.
Counters track the proportion of small cards to face cards and aces. At a certain point, the deck turns “positive.” The higher proportion of face cards means every hand played will generate long term profit for the player — not the house. This is because profit comes from doubling, splitting and hitting blackjack (natural 21). All of these are more frequent when there are more high cards in the shoe.
To take advantage of this edge, counting players must boost their bet size. Without this bet size boost, money spent playing while waiting for the deck to turn positive would cancel out any wins.
There are multiple factors that affect whether a specific game is a candidate for card counting. The number of decks of cards in play, the rules on splitting and doubling down, and how the dealer reacts to a soft 17 all come into play. To get the best from counting cards, you need to find the games with the lowest house edge.
Level 3 card counting systems & true count explained
Card counting systems have three levels of complexity. The simplest systems are Hi-Lo Counts. You count low cards as +1 and high cards as -1. The higher the count, the bigger the proportion of high cards to low cards.
Advantage players will increase their bets once a specific count is reached. To be sure that they have an advantage, they need to translate the current total into the “true count” first. This involves dividing the count by the number of decks still in play. If the count is +10, with five decks remaining in a six-deck shoe, then the “true count” is 10/5 = 2. This means games like double-deck blackjack are better for counting. Players do not need to play through those first decks in the shoe while waiting for the true count to be positive.
Level two and level three counting systems are more accurate. They assign +2 to some cards and +1 to others. This splits the twos and sevens from cards three through six, with some systems also counting nines differently. There are systems with separate counts for aces. Your bet sizes need to increase in line with the positive count — for example adding a unit every time the true count increases by two points.
If you are new to card counting, then a simple Hi-Lo Count is the place to start. Once you have mastered keeping track of the count while playing each hand perfectly and chatting with the other players, you will be ready to move to the next level.
Examples of card counting systems
The systems below range from level one to three. These are five of hundreds of possible systems, giving you an overview of how different systems vary in their complexity.
- Hi-Lo Count: This is a balanced count and is the first system that new counters use. You add one to the total for each card value from two through six — and subtract one for 10s through aces. Seven, eight and nine are neutral. You then divide this count by the number of undealt decks and round up as needed. You should increase your bets when the count is positive — betting more the larger the positive number that you count. The advantage of the Hi-Lo system is simplicity. Compared with other blackjack counts, Hi Lo card counting does lack precision.
- Hi-Opt 1 and 2: These systems were developed by Lance Humble, though they can be traced back to the 1960s. There are many more“neutral”cards compared to the Hi-Lo Count. Hi-Opt 1 uses aces, twos, sevens, eights and nines as zero for the count. Three, four, five and six are +1, and 10s through kings are -1. This system works best for single deck games. Hi-Opt 2 makes 10s through kings -2 on the count, with +2 for fours and fives, +1 for twos, threes, sixes and sevens. Aces, eights and nines are neutral. These are accurate systems, though with single deck games rare (and closely watched), it can be difficult to find a suitable game to use them.
- Ace-Five System: You will need to double your bet repeatedly as the count increases to make the Ace-Five System work. This is a simple count, involving only aces and fives. Every time a five is dealt, you add one, and every ace you see removes one. When the count is +2, you double your bet. Increasing it again for every +2 that gets added. If the count reverts to +1 or less, you go back to your initial bet size. The key advantage of this system is the simplicity. The always-changing bet size is likely to attract the attention of casino pit bosses.
- Uston Advanced Count: Ken Uston was a famous card counter, known for his flamboyant lifestyle. His most complex system is the “Uston Advanced Count.” Aces count as zero in this system. Fives are +3; 10s through kings are -3; nines are -1; twos and eights are +1; and threes, fours, sixes and sevens are +2. As with the other systems, you increase your bets in line with how positive the count gets — keeping the number of decks in mind. This system is designed to work best with a separate count of the aces. The complexity means that it is for experienced card counters only.
- KO Counting System: This system works like Hi-Lo, with an extra feature involving the insurance against dealer blackjack bet. It counts cards two through seven as +1, eight and nine as neutral and 10 through ace as -1. You should increase your bet at +2 or more (based on the true count). At +3 or greater, the insurance side bet becomes profitable and should be taken.
Which blackjack games are best for card counting?
Big casino resorts in Las Vegas, Atlantic City, downtown Detroit and elsewhere run a wide selection of blackjack games. At the lowest buy-ins (typically $5 and up per hand), the rules give the casino a huge edge over the players. Examples include paying 6:5 instead of 3:2 for blackjack, limiting doubles after splits and having the dealer hit on soft 17. These unfavorable rules can easily boost the house edge to 3% or even more. With six or eight decks, getting a true count can be difficult.
Contrast this with the best games. An ideal setup is a single deck game, with liberal splitting/doubling rules, dealer standing on soft 17, late surrender and 3:2 for blackjack. With a house edge of 0.5% or less, these games are restricted to the high-limit rooms. This type of game is most likely to be closely monitored. Suddenly increasing your bet would be an instant trigger for experienced casino staff to watch closely.
Successful counters look for games with the lowest natural house edge. They know the basic blackjack card counting strategy perfectly, so as not to give any edge back to the casino in the form of mistakes. If you do not know how to adapt blackjack strategy to subtle differences in the rules, then you are not yet ready to learn card counting techniques.
Is counting cards illegal in the US?
Counting cards is legal, unless you are using a mechanical or electronic device to help you keep track of the cards. Casinos do not want card counters in their games. People who are suspected of counting will be asked to leave the casino. Repeat offenses can see players banned — with trespass laws coming into effect if they attempt to return.
In 1979, Ken Uston took a casino in Atlantic City to court, challenging its right to ban “skilled” players. The court found in his favor. Rather than banning players, AC casinos now implement measures to stop card counting from working. They include regular shuffling, limiting players to flat bet sizes on each shoe and not allowing players to join a game mid-shoe.
Elsewhere, casinos will quickly ban players caught counting. This was the reason that the MIT team played in pairs. One player (betting small) would keep count, then signal to the big bet player when the count was positive. This player could then join the table, betting big amounts, while the original counter continued with smaller bets.
Card counting in other casino games
Very few casino games use a shoe containing several decks of cards. Casino poker variations like Caribbean stud or Ultimate Texas Hold ’em have a continual shuffle system, where a fresh shuffled deck is used for each hand. Baccarat does use a shoe, though it is not suitable for counting due to the complex scoring rules. Edge sorting is used in baccarat, though it is considered illegal in many jurisdictions.
This leaves blackjack variations like Spanish 21 and Free Bet Blackjack as the only candidates for card counting systems. Many variations of blackjack have a higher house edge than the main game. Spanish 21 removes 10s from the deck — starting the count on a negative.
Experienced advantage players use card counting to beat optional side bets. This requires a separate understanding of how each side bet works, with a counting system developed separately. Separate aces counts in blackjack can determine when the insurance against dealer blackjack bet becomes profitable.
Is it possible to count cards online?
Online casinos in regulated states have both software-based and live dealer blackjack options. They also have a range of games with different rules and side bets. Add in the game variations based on the 21 concept — and you will find a wide array of choices.
Advantage play through card counting is not possible at online casinos. Software based games use random number generator software to shuffle the cards for every hand. This means no count is possible. Live dealer games that are dealt in real time use eight deck shoes. What they do differently from brick and mortar casinos is reshuffle after around half of the cards are dealt. This makes it hard to spot situations where there is a positive true count. Add to this software that will instantly detect the bet sizing changes associated with counting.
What you can effectively do online is practice your counting skills. There are live dealer rooms at many of the biggest online casino brands, including Golden Nugget and BetMGM. You can enjoy a game and learn to keep score of the count while you play. Starting with simple systems like Ace-Five and Hi-Lo is ideal — you can move on to the more advanced systems as you gain experience.
If you live in a state with legal online casinos, make sure you keep a close eye on the casino bonus and promotion offers. You never know when a bonus aimed at blackjack players will become available.
Wrapping up: Card counting in blackjack
Card counting has been a part of blackjack since the 1960s. Famous players including Humble and Uston published books on beating the house. Many of them are now considered among the classics of gambling literature.
Counting cards in blackjack gives you an edge over the house when there are relatively more high cards in the deck. This takes advantage of the player’s option to split, double down and to take insurance against dealer blackjack. Counting systems are graded into three levels, depending on their complexity. More complex systems are more accurate — though harder to use.
There is an Achilles’ heel for card counters. To make your knowledge of the count profitable, you need to significantly boost your bet sizes when the odds are in your favor. These bet size increases are a flag to casino staff to watch your play closely — which leads to card counters being banned. Card counting is not illegal, unless you use a device to help you keep track.
Online casinos are the perfect place to practice your card counting skills. You will not be able to get an advantage from them — as safeguards are in place. Live dealer casinos show a real table, making this the ideal way to find the right card counting system for you ahead of your next visit to a brick and mortar casino.