In the game of 21, a player’s probability of winning depends on the cards still in the shoe. It didn’t take players long to figure out that if they could keep track of which had already been played and which were still in the shoe to be dealt, they could gain an advantage against the casino.

The idea behind counting cards is to figure out whether the shoe (a nickname for the collection of decks used in a blackjack game) contains more cards that give you an advantage or more cards that favor the dealer. Card counters are simply watching the cards disappearing from the game so they can place larger bets at less risk, if the shoe favors them. Gaining an edge by varying your bets depending on the cards remaining to be dealt requires a card counting system of some sort.

**Examples of Blackjack Card-Counting Techniques**

Card counting methods all assign positive, negative, or neutral values to every card in the game. Counters adjust the value of a hand based on the value of every card that gets played. In other words – what is the effect of removing the card from the game?

Statistically, speaking, a deck loaded with high-value cards benefits the player more than the dealer – in casino blackjack; the dealer has to hit hands in the 12-16 range while a player can take the option of standing. If a player knows that a deck contains a large number of ten point cards, he can bet more conservatively than the dealer. A shoe made up of more high-value cards also increases the chance of landing a natural blackjack (an ace paired with any ten-value card, a hand that pays out at 3:2). Low cards increase the count – by being removed from the game, as they increase the ratio of high cards to low cards in the game.

**Hi-Lo Card Counting**

A perfect example of this most basic counting formula is the High Low or Hi-Lo method, designed by a man named Harvey Dubner. In this system, one point is subtracted from your basic running count for every ten, Jack, Queen, King or Ace that is dealt, while a point is added for any card with a face value of 2-6. In this system, cards 7-9 are neutral and don’t affect the count at all. Count all the way through a standard 52-card deck and you’ll see that the overall point value of the deck is zero, according to Dubner’s system.

The High-Low system is considered a single-level or level-one count, because a running tally of the cards will never get bigger or smaller by more than one unit. First, figure out how many decks are in the shoe – let’s use a four-deck game for simplicity’s sake. Regardless of the size of the deck, the value starts at zero at the beginning of the game. Based on the point system described above, a series of ten cards out of this shoe that looks like this – 4, 6, 10, 7, Q, A, 8, 4, 2, and 2 – would equal a running count that looks like this – 1 +1 -1 +0 -1 -1 +0 +1 +1 +1, leaving you with a final total of +2.

Now to get the real value of the shoe after these first ten cards, you need to divide that number by the number of decks still in the shoe – this is what counters call the True Count. No need for any complex math here; if our running count is +2 and there are nearly 4 decks left, then we simply divide 2 by 4 for a total of 0.5. To keep it simple, many High Low counters round all half-point values up, so that our final count in this example is +1.

So what do you do with that information? You should place more bets the higher your true count gets. Of course, over time new systems have been developed to help players figure out the ratio of high-value to lower value cards in the shoe. Edward O. Thorp, a fascinating character that’s also famous for building the world’s first wearable computer, published a book called Beat the Dealer in 1962 that was the first to show that players could gain an advantage in blackjack by keeping a count. A math professor at MIT, Thorp wrote the book as an academic essay, the first use of computer simulations applied to games of chance. The book hit the New York Times bestseller list, and modern card counting was born.

The Hi Lo method described above is just one of many different point systems used in blackjack strategy. If you want to learn to track the point values in a game, dozens of methods exist that assign different values for different cards, with the purpose being to keep track of the ratio of high cards to low cards still in the game.

**Methods for Counting in Blackjack**

Finding a system that is simple enough to use is more important than finding the statistically best method – whatever point value system makes sense to you is the one you should use.

**Hi Opt**

Sometimes called the Einstein (though the inventor is Charles Einstein, not the world-famous physicist Albert), this is a variation on Hi Lo that is really easy to learn once you wrap your head around that basic method. In fact, values of points are almost identical. The big difference in Hi Opt is that aces and twos are neutral cards.

The name of the system should be a big clue to what it is – an optimized version of Hi Lo. Developed to give a more accurate count than the point values assigned in the original system, Hi Opt proponents say that keeping track of aces separately (by wiggling or tapping your toes, for example) makes this point tracking system even more accurate. For example, knowing the number of aces still in the shoe (along with your Hi Opt point count) would affect your strategy in terms of taking insurance or doubling down.

**KO**

Sometimes called the Knockout method, this is another counting system based on Hi Lo point values with a slight twist. Cards are worth the same in the KO method as they are in Hi Lo, except that sevens add a point, instead of being of neutral value. That makes KO an unbalanced system – if you add up all the point values in the deck, the total does not equal zero.

The point of unbalanced systems, and the thinking behind the KO system is to make it easier to count multiple decks. Without the need to turn your running total into the true count described above, keeping track of the deck is easier.

**Red 7**

A system that combines both the Hi Lo and KO’s take on sevens is known as Red7. When counting using this system, the seven of diamonds and the seven of hearts add one to the count, as though they were another low-value card. In this system, the seven of clubs and the seven of spades are neutral cards. The imbalance created in the total count of a single deck allows blackjack players to avoid having to compute a true count.

In Red7, all counts of 0 or better indicate that the shoe favors the player. In order to keep this standard across all numbers of decks, your starting point total changes. Multiply the total number of decks in the shoe by -2 to get your starting point; for example, a four-deck game requires a starting total of -8.

**Revere Count**

Invented by pro blackjack player Lawrence Revere, this is a more complex way to keep track of the point total than the ones we’ve looked at above. In Revere’s system, the deck is broken up into groups, with each group worth a set point amount.

With Revere, all twos and sevens are worth +2. All threes, fours, and sixes are worth +3. All fives are worth +4, and only the eight is neutral. This system removes one point for nines, takes away three points for 10s and any face card, and all Aces are worth -4.

With these point values, any count on the high side means it’s a good time to start increasing your bet, since a high ratio of high-value cards are left. The problem with advanced systems like Revere’s is that you may as well memorize the entire deck and forget about the count altogether – the wide range of point values make keeping track of cards in blackjack significantly more difficult. Revere’s method uses four different values for cards in the game, and requires a lot more practice to use in a live game.

These are just a few of the various ways of keeping track of cards in blackjack. The point value assigned to a card in the game of 21 depends both on its face value and the method you’re using for keeping a running count.