Card counting has been a persistent thorn in the side of casinos, both physical as well as online, for a long time. It’s not cheating, but is still frowned upon by casino operators because it helps the players win too much. In particular, card counting is used in blackjack. In this article, we’ll explore what card counting is, some famous examples of card counters, and why card counting has fallen out of use especially with online blackjack’s introduction, like the blackjack games hosted on LegaBet. 

Table of Contents

What is Card Counting, and How is it Done?

1. What is Card Counting?

2. How is it Done?

3. The MIT Blackjack Team

4. Casinos Strike Back

What is Card Counting?

So what exactly is card counting? To put it simply, it’s a mathematical strategy in Blackjack, used to count the number of remaining cards in a dealer’s deck, which helps a player determine what cards remain. This blackjack card counting allows the player to figure out who has the advantage. 

Players who do this are known as card counters.

Their goal is to beat the casino house edge, which is done by keeping a running count of high and low valued cards that have been dealt. For example, they generally bet more when they have an advantage, and bet less when the advantage is on the dealer’s side. Depending on the composition of the dealer’s deck, these players will also change strategies on an impromptu basis.

How is it Done?

Blackjack card counting is based on statistical evidence that high value cards like aces, 9s, and 10s benefit the player, while low cards like 2s, 3s, 4s, 5s, 6s, and 7s benefit the dealer. Their reasoning is based on blackjack strategy, which requires players to score higher than the total value of a dealer’s cards, while not going over 21 at the same time. The player needs to score higher than the total of the dealer’s cards, while not exceeding 21 themselves. If the dealer exceeds 21, the player wins. High value cards are beneficial because:

1. High cards make the player’s total score much higher, which means they are likelier to hit Blackjack.

2. Doubling down increases expected value. The increased ratio of tens and aces makes the probability of success higher.

3. Players usually double down on hand values like 11, 10, and 9. If a player draws another high card while holding these values, their hand is more likely to beat the dealer.

4. High value cards give players more splitting opportunities.

5. If an insurance bet is in play, players can turn a higher profit by increasing the odds of dealer blackjack.

6. High value player cards also increase the chances of  the dealer going bust (losing), if the dealer ends up showing a low card. 

On the flip side, low cards benefit the dealer in blackjack games. According to the rules, the dealer’s hand needs to be stiff, between the values of 12-16. Low cards are less likely to make them exceed 21. 

You don’t need to be some sort of mental genius to become a card counter. There’s no tracking or memorizing specific cards. Instead, a point score is assigned to each card, which estimates the value of that card. The sum of these values is then tracked with a running count.

Card Counting Systems

The most basic types of card counting systems usually assign positive, negative, or zero values to each card. After a dealer deals a card, the card counter adjusts their count by the card’s value. Low cards removed from a deck will increase the count, because this increases the percentage of high cards in the deck, and vice versa for high cards. For example, a counting system could subtract 1 from the count for each ten, jack, queen, king, or ace dealt, or  add 1 for any card between 2 and 6 dealt. 

For the purpose of the count, 7, 8, and 9 have the value of zero.

Effectiveness of Counting Systems

All card counting systems try to assign point values that roughly correlate with a card’s effect of removal (EOR). This is the roughly estimated effect on blackjack games when removing any given card from play, measured against the casino’s house edge. The larger the ratios between point values, the better the correlations to actual EOR, which makes the system more efficient. Card counting systems like this are usually labeled according to their efficiency, such as as level 1, level 2, level 3, and so on. 

There are also many side counting techniques that can be used in blackjack strategy. This includes special counts for games with unusual conditions, such as over/under side betting. 

Having said that, of course there are limitations to card counting. At higher level counts, keeping track of the amount of data gets harder and harder, and this may affect a player’s speed and accuracy. 

Odds of Success

There are many other card counting systems, each with their own advantages and disadvantages. But the problem is, even with all the blackjack strategy on their side, a single card counter only has a small advantage when counting cards. An average card counter who places bets appropriately in a game with six decks has an advantage of approximately 1% over the casino. Blackjack statistical variance is high, and players may need hundreds of hours of play to turn a decent profit.

The MIT Blackjack Team

And that’s why card-counting is usually done in groups, with each group of counters playing at a single table to maximize efficiency. In a group, the amount of variance in a game is reduced. Players can cover for each other in case of mistakes, split the profits, and reduce suspicion by doing things like making bad bets.

One of the pioneering groups of card-counters was the MIT Blackjack Team, a collective of students and ex-students. The students were from Massachusetts Institute of Technology, Harvard University, and other leading colleges, operating successfully from 1979 through the beginning of the 21st century. 

Casinos Strike Back

While card-counting isn’t illegal, casinos really, really don’t like being on the losing end. So they struck back. After a lot of investigation and surveillance, one by one these card-counting students were caught and banned permanently. 

 Today, card-counting is much harder to pull off. Casinos have countermeasures such as continuous shuffle machines (CSMs), which allow the dealer to simply return used cards to a single shoe to allow playing with no interruption. They can also spot card-counters easily most of the time.

Online blackjack, like the games on LegaBet, also makes it harder to card count since there’s no dealer involved to shuffle the cards. Now that playing blackjack online is gaining popularity, card counting may decline even more.