Advantage Play in Blackjack

When you're gambling with a casino, one of you has an advantage over the other. Usually it's the casino which has an advantage over you, but if you're familiar with certain techniques, you can get an advantage over the casino.

This page about advantage play in blackjack offers an overview of which techniques blackjack players commonly use to get an edge over the house.

Before we get to that, though, we start by talking about how a mathematical advantage works in the first place.

Mathematical Advantage Explained

This is a fundamental part of understanding advantage play, in fact. It requires a little bit of understanding of how probability works.

Examples are probably the easiest way to get this point across, so we'll provide a couple to help illustrate this explanation.

Example 1 – Coin Toss

Let's suppose you're playing a casino game based on a coin toss. You guess whether or not you're going to get heads or tails. Half the time you'll win, and half the time you'll lose, right?

1Some Barcrest games don't have any bonus rounds
2The first impression of this slot is that it might have

But what if you have to bet $2 every time, and you only win $1 if you're right?

It's easy to see how in the long run the casino is going to come out ahead in this example, isn't it?

Suppose you guess at 100 coin tosses and guess right 50 times. You win $50. But you also guess wrong 50 times, and you lose $100 on those wrong guesses. The casino's net profit over those 100 coin tosses is $50.

That's a clear example of how a casino gets an advantage over a player.

But wait, you say. That's a crazy example because no one would ever take such a bet.

And yes, it is an extreme example, but it's meant to be illustrative. The casino is more likely to create a situation where you have to bet $1.10 to win $1.00. They might call that extra 10 cents an "ante" bet or something like that. When you play blackjack in Oklahoma, you have to place a 50 cent extra bet on every hand as an ante, so it happens.

Every casino bet works this way, though. If you place enough bets, the math will work in the casino's favor.

Example 2 - Roulette

Here's a real example from a real game—roulette.

An even-money bet on black or on red seems like a 50/50 proposition until you look a little more closely at the roulette wheel. Yeah, almost half the slots are black, and almost half of them are read.

But two of those slots are green.

If you bet on black, the casino wins if the ball lands in a red slot.

But it also wins if the ball lands in a green slot.

The same holds true if you bet on red. The casino wins if it lands in black—OR if it lands in green.

There are 38 numbers on the roulette wheel. 18 of them are red, 18 of them are black, and 2 of them are green.

If you place 38 bets in a row on black, the math says you should win 18 of those bets and lose 20 of them. The same holds true of 38 bets in a row on red.

Of course, in the short term, you might end such a session winning more than you lose, but the odds are you'll come close to losing two of those bets.

The casino depends on the law of large numbers to make its profit.

As you place a larger number of bets, the more likely you are to see actual results that mirror the probably results.

A casino sees hundreds of thousands of bets per month—maybe even millions, if it has a lot of traffic. So eventually the math results in the casino winning.

Blackjack is a more complicated game, mathematically, than roulette, but it usually offers the house an edge of about 1% over the player. That means you'll lose an average of $1 for every $100 you bet. And that's assuming you use correct basic strategy to make your decisions. An unskilled player might make several bad decisions per hour, which means she'll likely lose 2% to 4% of every bet.

But you can use certain techniques to flip that edge around and get an advantage over the casino. Using such techniques is called "advantage gambling".

Casinos hate advantage gamblers.


The first advantage gambling technique we'll discuss is just flat-out cheating. To be fair, most people who use the expression "advantage gambling" or "advantage gambler" are referring to techniques that fall outside the definition of cheating. But it's easy to see how you might get an edge over a casino by cheating.

Of course, cheating is illegal in most states. In Nevada, which is home to Las Vegas, cheating is a felony. You can find plenty of interesting pages on the Internet about players who have been caught cheating in Las Vegas and spent time behind bars.

How would you cheat at blackjack?

Cheating is when you change the parameters of the game in your favor.


Suppose you were able to change the amount you bet AFTER you knew whether or not you'd won or lose?

This is called "past posting". It's all but impossible to pull off at a blackjack table, but it's clear to see how you could get an advantage by doing this. You'd simply increase the size of your bet by putting extra chips on top of your wager after seeing that you've received a blackjack.

Don't try this. You'll get caught. Casinos will prosecute, too.

Another cheating technique used at the blackjack table is the marking of cards with a sharp fingernail. If you're able to tell what even some of the face-down cards at the table are, you can get a mathematical edge over the casino.

This one's less likely to get you caught, but it's still a bad idea—especially since there are so many legitimate ways to get an edge over the casino in blackjack without having to cheat.

Cheating usually involves using a machine to get an edge or perpetrating some kind of fraud against the casino. Definitions vary based on your jurisdiction—in some places, the state and/or city don't even define cheating legally. In those cases, the definition (and enforcement) is left up to the local gambling authorities.

Comps and Rebates

Comps and rebates are rewards offered by the casinos in order to encourage more action from players. In order to receive these comps and rebates, you usually need to join the players' club or the slots club at the property. In some cases you might be able to get some comps from the pit boss just by playing a lot at the tables, but most casinos prefer to track this sort of thing more closely than they used to.

How It Works

The casino has a points system which corresponds to how much you wager. When you're playing their slot machines or video poker machines, they can track exactly how much money you've wagered per hour. If you're betting $3 per spin and making 600 spins per hour, you're putting $1800 per hour into action.

When you're playing a table game, the casino will rate your play. If you're betting an average of $50 per hand on blackjack, and you're playing an average of 50 hands per hour, they'll base your comp rate on $2500 worth of action per hour.

They then offer rewards at a tiny percentage of your action. This might be as little as 0.2% or 0.3% of how much you've wagered.

In the examples above, a player would earn between $3.60 and $5.40 per hour in comps at the slots. The example blackjack player would earn between $5 and $7.50 per hour.

It's important to understand that the casino bases these comp amounts on the amount of action you're engaged in per hour, NOT on the amount you've actually lose.

You could win a huge jackpot on a slot machine and still receive a significant amount of comps based on how much you've played'even though you walked away from the casino a winner for the trip.

The casino banks on the long term expectation of the games. They're not interested in individual players who have individual winning sessions—at least not when it comes to awarding comps.

The casino has done the math on these games, so they expect you to lose a certain amount per hour. They also expect this amount to be greater than the amount of comps you earn.

But if you can combine those comps with another strategy for lowering the house edge, you can gamble at close to even or even get a slight edge over the casino.

Also, casinos offer special promotional time periods where they offer double points for your play. It's a lot easier to turn that tiny percentage into an advantage if it's doubled.


You're playing at a casino with a generous comps program. They award 0.3% of your play in comps.

On Tuesdays from 2pm to 4pm, they offer double points. So now you're getting back 0.6%.

This particular casino also has really favorable blackjack rules. The house edge on their game is only 0.5% as long as you use perfect basic strategy.

When you take into account the 0.6% you're getting back, you're actually playing with a 0.1% edge over the casino.

That's called "comp hustling". You can find detailed advice on how that works in Max Rubin's book, Comp City. It's a little dated now, but the advice still applies, and the math still works the same.

When you combine comp hustling with other advantage techniques, it increases your edge over the house.

Counting Cards

Counting cards is probably the best known advantage technique in the casino—it's certainly the best known advantage gambling technique in blackjack.

But a surprising number of people don't understand how it works. They think you have to be some kind of mathematical genius or idiot savant (a la Rain Man) in order to pull it off.

The reality is that it's a lot easier to count cards than most people think.

That's because you don't have to track exactly which cards have been played and which ones are still in the deck. You only have to track the approximate ratio of high cards to low cards.

How Card Counting Works

A "natural" in blackjack pays off at 3 to 2. If all the aces were eliminated from the deck, you'd be unable to ever get a natural, which would tilt the odds further in the casino's favor. The same would hold true if you were out of cards ranked 10.

The reverse holds true, too, though. If you removed all the cards in the deck except for the aces and the 10s, you'd have a situation where you'd be MORE likely to be dealt a natural, tilting the odds in your favor.

In a real game, though, you'll seldom encounter a situation where all of these cards are gone. But you an estimate the ratio of high cards to low cards. If there are a relatively large number of high cards compare to low cards, your odds of getting a natural improve. Since the house edge in blackjack is low to begin with, betting more when you have a better chance of getting a natural gives you an edge over the casino. You would, of course, bet less when you don't have a favorable deck.

The easiest way to track this ratio is by assigning a value to the high cards and a value to the low cards and keeping a running count. It's common for high cards (10s and aces) to be given a value of -1 and for low cards(2s through 6s) a value of +1. When the count is positive, there are a relatively large number of high cards in the deck compared to low cards. When it's 0 or negative, the reverse is true.

The card counter raises her bet when the count is positive and lowers her bet when it's negative.

This gives a counter an advantage of anywhere between 0.5% and 2% depending on the rules for that particular game and the size of the player's betting spread.

Multiple methods of counting cards exist, each of which varies the values for various cards. Each of these has its advantages and disadvantages over the other counting systems. They all follow the same principle, though.

The Problem With Card Counting

Casinos hate card counters.

Since you're not using a device and you're not changing the conditions of the game, you're not cheating—at least not legally. But the casinos are so opposed to the practice that they reserve the right to ban you for life if they think you're counting cards.

Of course, different casinos have different policies. Some might just ask you to stop playing blackjack there. Others might run you off for the day. And some might ban you for life.

David Sklansky, in his book, Sklansky Talks Blackjack, suggests only playing at a particular casino for an hour at a time. He also suggests hitting a particular casino during different shifts. He also suggests not playing at a particular casino every day. These are countermeasures to help you avoid getting caught.

Card counting is a technique that Max Rubin suggests using in conjunction with comp hustling to maximize the amount of value you get from your casino vacation.

Edge Sorting

You're not allowed to do anything to mark cards. That's cheating.

But it's possible for cards to develop irregularities during regular play.

It's also common for cards to have irregularities in the patterns on the back of them.

It's not cheating to notice those irregularities and take advantage of them.

Players who are able to identify groups of cards which are important—in blackjack, that would include 10s and aces—are able to get a big edge over the casinos. The concept works in a similar way to counting cards. If you're able to recognize a group of cards with lots of aces and 10s in it, you can raise your bets to take advantage of the 3 to 2 payout.

Edge sorting is used to get an advantage in multiple casino card games, including baccarat and Caribbean stud.

Advanced Advantage Play by Eliot Jacobson

Hole Carding

Hole carding is an advantage play technique in which the players get a glimpse of a card that's supposed to be out of sight. In blackjack, this almost always refers to the dealer's hole card. It should be obvious why knowing what the dealer has in the hole offers an advantage to the player.

From a legal perspective, courts in Nevada have ruled that hole carding is legal so long as the player is seated in the appropriate place and isn't using a device to help him get a glimpse of the dealer's hole card. Players who are able to pull this off just look for opportunities where the dealer has gotten sloppy.

Not all dealers offer the opportunity to get a glimpse of the hole card. But the best spot for catching a glimpse is first base or third base. First base is better. The reasons are simple enough, too. Those are the spots closest to the dealer.

This sounds too good to be true, but it gets better. When you're counting cards, you can get an advantage of 0.5% to 1% over the casino.

But if you can spot the dealer's hole card, you can get an edge of around 13% over the casino.

That's huge.

James Grosjean's Beyond Counting Book

You can also read about hole carding in Ken Uston's Million Dollar Blackjack.

Shuffle Tracking

For some of us, shuffle tracking is the most difficult advantage play concept to understand. The idea is that certain groups of cards stay more or less together when the deck is shuffled. These groups are called zones, and if you can track where they are in the shuffle, you can get an edge.

Shuffle tracking is often used by card counting teams in conjunction with card counting techniques. Since players often get to use a cut card to cut the deck, they can use this to their advantage by making sure the deck starts off with a clump of cards rich in aces and tens.

The best resource we've found about shuffle tracking is at . That page was originally posted at rec.blackjack and later at, the latter of which is now defunct.


Various methods of getting an edge over the casino in blackjack exist. The blanket term "advantage play in blackjack" refers to all of them: counting cards, shuffle tracking, hole carding, and edge sorting. Cheating, as a general rule, can get you an edge over the casino, but most people who discuss advantage gambling are talking about activities which aren't considered cheating.

Counting cards is probably the best known and perhaps the easiest technique to use. But casinos watch for card counters like hawks. Also, techniques like hole carding can get a greater edge for the player.
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