Blackjack card counting

By Ville Saari. Updated:

Bojoko helps you learn card counting. By counting cards in blackjack, you'll have an idea of what cards are left in the deck and how this affects your odds of winning. Card counting helps you plan and time your bets. A successful card counter may even turn the odds around and gain a slight edge over the casino.

Card counting is a skill that takes some practice to master. To make it easier, we've created a handy card counting drill. It gives you instant feedback and helps you count up to 8 decks.

In this guide, we'll teach you the Hi-Lo count, the most popular card counting method. In addition, you'll get introduced to a few more advanced card counting techniques and the countermeasures casinos have against the card counters.

Casinos where to try card counting

Here's a list of casinos with the best selection of live dealer blackjack tables. Remember, card counting doesn't work in RNG blackjack or against the continuous shuffling machine. Instead, you'll need a table with a physical shoe of cards.

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Learn more about card counting in blackjack

Card counting helps you gauge which cards are left in the deck without remembering every single card played. To make learning this technique easier, we've built a great tool:

[button card counting drill]

In addition, we show you how card counting works and discuss the effectiveness of card counting in general:

We also recommend checking out our other blackjack pages:

Blackjack card counting

What is card counting?

Card counting is a way to keep track of cards already played and to gauge what cards are left in the deck. Knowing when the deck is "hot" or "cold" helps you plan your play and adjust your bets:

To keep track of this, you don't have to memorize every card coming from the shoe. This is where the Hi-Lo count comes in.

By counting cards, you can improve your RTP by 1 percentage unit. Although this might not sound like a lot, over several hours of gameplay and hundreds of hands, this can have a serious impact on your bottom line.

There are several card counting strategies for blackjack. We'll walk you through the main ones shortly.

Card counting trainer

Learning card counting takes some time and patience. We wanted to make this easier and that's why we've built a card counting trainer to help you master the Hi-Lo count.

The card counting drill is part of our Blackjack Trainer by Bojoko app for iOS and Android. You can download the whole app to you mobile device, or try the stand-alone version of the card counting drill here:

Card counting drill
Game background

How to use the card counting drill

  1. Choose how often the game asks for the count
  2. Select the number of decks to count
  3. The game plays automatically according to the basic strategy
  4. You'll need to keep a running count, i.e. add the cards of the current hand to the previous tally
  5. The game asks you the count after a certain number of hands has been played and tells you the right answer if you made a mistake
  6. You can check the card values and other instructions by clicking on the 🛈 icon on the left-hand side of the screen

Hi-Lo card counting system

The Hi-Lo system is arguably the easiest and quickest blackjack card counting strategy to learn. Every card in a 52-card deck is assigned a value of +1, 0 or -1. Here's how each card is valued:

blackjack HiLo card counting

The Hi-Lo card counting strategy is known as a "balanced system" where the sum of all cards in a 52-card deck is 0.

EXAMPLE: You're dealt 10 and 7; the dealer is showing a 6. You stand, the dealer reveals an Ace and you push. What's the count?

Learn the running count

Once you have memorised the values for each playing card in blackjack, you can try to practice the Hi-Lo running count needed.

The easiest way is to try the card counting drill we mentioned earlier. However, there are some more traditional, low-tech solutions available.

The most basic practice technique for mastering the running count is taking a 52-card deck and counting the cards one by one using the Hi-Lo card values above. Once you have reached the end of the deck, your count should be at zero.

In an ideal world, you should be able to accurately count a 52-card deck and reach zero within half-a-minute or less. That speed will be vital when you implement the Hi-Lo card counting strategy for real at the blackjack tables.

How to improve your counting technique

Another clever technique to improve your Hi-Lo running count is to remove a random card from the 52-card deck without spotting its value. Proceed to count the rest of the deck and you should be able to recognise whether the card you removed was a +1, neutral or -1 card. If you've calculated incorrectly by the 51st card, you haven't practiced hard enough!

Once you feel confident that you have grasped the Hi-Lo running count, get a friend or family member to play the dealer role and play one-hand rounds against them. After a few rounds, there should still be multiple cards left in the deck. In order to monitor how well you've been keeping a running count, add your latest running count to the cards left in the deck. If the end number is zero, you've mastered it. If not, practice makes perfect.

TIP: Card counting at blackjack tables in land-based casinos is frowned upon (but not illegal). Try to avoid making it obvious that you are keeping a running count, as this could lead to your dealer alerting the pit boss.

How to use true count for betting in multi-deck games

Learning to keep the ‘true count' is a useful skill for blackjack card counting when you play multi-deck games at a casino.

True count gives you a better idea how "hot" the deck is. It incorporates the remaining decks to your running count via a simple calculation:

True count = Running count ÷ decks remaining in the shoe

If you don't factor the remaining decks into your calculations in a multi-deck game, you'll have an overly optimistic view of your chances to win.

True count tells you how many MORE high cards there are compared to the small cards, if there were only one deck remaining in the game.

The true count at a multi-deck blackjack table will require you to accurately determine how many decks remain in play.

EXAMPLE: If your running count is +8 and there are four decks remaining in the shoe, you will divide your running count of eight by four remaining decks, resulting in a true count of +2 (8 ÷ 4 = 2).

If your calculation ends in a decimal number such as +3.25 or +3.50, you must always play the hand as if the true count is +3 and -3 for a negative count. Never round up your decimals! This will limit your risk exposure and prevent you from betting big too early in case the true count is inaccurate.

Advanced techniques based on the Hi-Lo count

There are ways you can use the Hi-Lo card counting system to deviate from basic blackjack strategy. These moves help you vary your gameplay, particularly in multi-deck games where the ‘Surrender' option is available to players.

The Fab Four

There are four true count variations known as the Fab Four. These variations were devised by a blackjack professional Don Schlesinger, who sought ways to improve his profit where Surrender was an option.

According to the Fab Four strategy, you should surrender when:

  1. You have 15, the dealer has 9 and the true count is +3
  2. You have 15, the dealer has 10 and the true count is 0
  3. You have 15, the dealer has A and the true count is +2 (dealer hits soft 17) or -1 (dealer stands on all 17s)
  4. You have 14, the dealer has 14 and the true count is +4

Schlesinger also devised 18 additional variations to the basic blackjack strategy that are considered by experts to help execute "perfect play".

The Illustrious 18

The "Illustrious 18" are advanced blackjack moves requiring even more concentration and effort to perfect. There are 18 game decisions that players can make based on the current game situation and count:

blackjack illustrious 18 chart

Unbalanced card counting systems

If you can't handle the mental arithmetic necessary to master Hi-Lo card counting, there's an alternative. An unbalanced card counting system does not add up to zero at the end of a 52-card deck.

Consequently, players of unbalanced card counting systems do not need to convert their running count into a true count. Here are a couple of the most common unbalanced systems:

The Key Card Count

Devised by Fred Renzy, the Key Card Count requires only a handful of cards to be counted in the following way:

The system is unbalanced as the sum of all low cards is +8 for each deck, while the total of all high value cards is -6, resulting in a +2 imbalance.

With this strategy, you begin your count at +18 once the decks have been shuffled. Whenever you spot a 4 or a 5, add one to your count and minus one from your count whenever a 10 or black Ace is dealt.

Based on your count, you should:

The Red 7 Count

The brainchild of Arnold Snyder, this system requires you to count cards in the following way:

To use this system, start your count at -2, multiplied by the number of active decks. If you're playing a six-deck game of blackjack, you should start at -12. Once the running count reaches zero or a positive figure, you have an edge and should raise your stakes.

Why red sevens? The logic to counting red sevens as +1 is to create an imbalance in the system. Under this card counting strategy, you count black sevens as neutral. Because there are an equal number of red and black sevens, this strategy creates an imbalance in the score. From this, you can work out the true count without the need for complex maths.

Countermeasures against card counters

Although card counting is not illegal, casinos don't like players who do it. Casinos spend a lot of energy to spot card counters, ban them and make sure they don't come back.

These are the common countermeasures of card counting used by land-based casinos. You can watch out for them at the blackjack tables:

Frequent card shuffling

Most land-based casinos will counter the threat of card counting by shuffling their decks more frequently, particularly after players increase their bets. In some ways, casinos are hurting themselves with this card counting countermeasure, as more shuffling reduces the number of hands played per hour.

The point at which the cards are shuffled is known as deck penetration. If the dealer shuffles after 36 cards from a single deck have been used, this represents 70% deck penetration. Casinos will often have set percentages, such as 50%. However, this can change based on how players are betting and if card counting is suspected.

Increased decks per shoe

The addition of more card decks per shoe also makes card counting much more difficult. By adding more decks, casinos are increasing the variables, making it harder to deduce what's left in the shoe. Sometimes casinos won't make it clear just how many decks are in the shoe either.

Concealing the number of decks in play

Cards will appear sloped inside the shoe so as not to make it obvious when you are down to the final deck of cards.

Casinos will conceal their tray of cards that have already been dealt from the shoe.

Casinos may vary when they change the shoe. By replacing the shoe at random points, it prevents players from finding patterns.

Blackjack 6:5 tables

In recent years, land-based casinos have taken the decision to bring single-deck blackjack to their tables. However, it might not be a good time to rejoice. That's because even though it might be easier to card count again, the odds of a natural blackjack – formed with an ace and a face card – have been moved in favour of the house.

Traditionally, the payout of a natural blackjack is 3:2, but these single-deck tables only offer payouts at 6:5, which is something to bear in mind.

Dealer interaction

When it comes to casinos catching individual blackjack card counters, the ‘pit boss' will encourage dealers to chat to you in between hands to break your concentration. If a dealer gets a feeling that you are ignoring their advances and focusing solely on the outcome of the cards, they may choose to signal the pit boss that you may be counting cards.

Enhanced surveillance and analysis

You might not see it from the tables but land-based casinos are investing heavily in surveillance and computer analysis software. This helps them pinpoint suspicious behaviour, e.g. card counting. Casino security can increasingly detect card counters based on their behaviour after winning hands, displaying stable emotions despite betting big on a hand.

Card counting at online casinos

Card counting is significantly harder at online casinos than at brick-and-mortar establishments. There are two main reasons for this:

Below, we look at these two ways to run online blackjack in more detail.

Random Number Generators (RNGs)

Online casino game providers need to make sure the results of each round are completely random. That's why they use computerised algorithms called Random Number Generators (RNGs). These blackjack versions are 100% digital: the cards and the table only exist as ones and zeros on the game server.

In terms of fair, transparent gameplay, the use of RNGs is a positive step. However, it's something of a nightmare for card counters. Online blackjack games using RNGs shuffle their cards after every single hand. Since the count is lost after each deal, counting cards in RNG blackjack doesn't work.

Live dealer blackjack

A few years ago, many live dealer studios had Continuous Shuffling Machines (CSM). Especially the common draw blackjack versions, where all players make decisions on the same hand, were powered by a CSM.

A continuous shuffling machine does what the name suggests: the discarded cards go back to the machine and it produces an endless stream of completely random deals. Card counting doesn't work against a CSM.

Luckily for live dealer blackjack aficionados, most game providers have switched to using traditional card shoes. This enables card counting.

However, there are usually 8 decks per shoe and the deck penetration is often 50% or under. This means the dealer will change the shoe after only 4 of those 8 decks have been played. In addition, the pace at live dealer blackjack is fairly slow, meaning opportunities for big bets come less often.

As a result, getting any advantage out of card counting, you'd need an exceptionally high count. You'd have to spend hours upon hours waiting for your moment, and play with quite high bets when that moment comes.

Finally, online casinos don't like card counters any more than their land-based counterparts do. If your gaming patterns raise any red flags, you may be banned from playing at the casino.

Card counting and responsible gaming

Learning card counting can give you an idea that the house edge disappears and turns in your favour. Granted, in optimal conditions, card counting can give players a slight advantage over the casino. However, casinos do their best to eliminate this advantage.

Unless you're one of the high rollers who can dictate their own rules to a casino in exchange for their patronage, it's unlikely you'll turn the odds in your favour.

Even if you manage to count cards, there's still an element of risk involved. Even though the count is high, the cards can come out of the deck in an order that suits the dealer better than you. Just like a player can win even against the house edge, the house can beat you despite you counting cards.

Bojoko is an advocate of responsible gaming and this means treating all forms of gambling as entertainment instead of a way for players to make money. So if you decide to count cards, manage your expectations.

Card counting FAQs

The most intuitive way to learn to count cards is to try our card counting trainer. You'll learn the Hi-Lo counting system and get instant feedback as often as you want.

In RNG blackjack, card counting is of no use. The game is completely digital and shuffles after each round.

In live dealer blackjack, you can actually count cards. However, the pace of the game is fairly slow and the deck penetration quite low. Together, these conditions mean you'll have to wait for a long time for the odds of the game to actually turn in your favour.

Card counting is NOT illegal in any way. Card counting as a genuine skill rather than a form of cheating. Being able to use your brain and remember the count of active playing card decks is merely a clever way to play the game.

There are no specific laws restricting the use of card counting strategies for playing blackjack, both offline and online. The reason why so many people think that card counting is illegal is that the strategy is frowned upon by casinos. By counting cards, you are reducing the game's house edge and maximising your chances of winning.

However, casinos are private entities and the owners are within their rights to refuse entry to card counters. Once an individual has been banned from a land-based casino, they may be breaking the law if they try to play at the same casino later. Banned players that re-enter a casino can be deemed to be trespassing, and that is a criminal offence.

Ville Saari

Article by:

Ville Saari

Ville is an industry veteran, who has written thousands of gambling-related reviews and articles since 2009. He is an IT engineer with a passion for game and strategy optimization, and to teach the world to play better.

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