Why Is Card Counting in Blackjack Illegal?

Unless you’ve been living under a rock, you’ve heard of card counting in blackjack. Even if you never go to the casino and have little interest in doing so, the image of the card counter is so prevalent in pop culture that it would be impossible to not at least have some idea about it.

But what is card counting in blackjack, really?

How does card counting even work?

Is it really illegal? If so, why? If not, why do so many people think it is?

This post answers all these questions about card counting and then some. Keep reading below to learn more.

How Card Counting Works

The first thing to understand about card counting is why and how it works.

In most casino games, every bet is being placed on an “independent event.” This means that the odds are the same regardless of what happened on the previous round.

Roulette is a good example. If you bet on a single number, the odds of winning are 37 to 1—every time.

You have 37 ways to lose and only one way to win.

But suppose that the casino left the ball in the pocket after spinning the wheel? A bet on a single number on the next spin would have odds of 36 to 1 because you’d have fewer ways to lose.

This would continue until the casino removed the balls from the pockets and started over.

Blackjack is similar. When a card gets dealt out of the deck in real money blackjack, it’s gone, and that changes the probabilities for the next hand.

And since the deck is randomized, you’ll sometimes wind up with a deck that has a higher proportion of aces and 10s in it than normal.

This is good for the blackjack player because aces and 10s are the cards you need for a blackjack.

And a blackjack pays off at 3:2 odds.

Increase the size of your bets when the deck is relatively rich in aces and 10s, and you’ll get an edge over the casino.

And that’s how card counting works.

You just keep a tally of low cards to high cards and bet more when there are more 10s and aces in the deck.

How to Count Cards

Learning how to count cards isn’t hard. You need to start with a system. The easiest system I know of is the high-low system, and I can teach you the basics in a couple of paragraphs.

You start by assigning a point-value to each card in the deck. Aces and 10s are worth -1 each. Sevens, eights, and nines are worth zero points. All the lowers cards, twos, threes, fours, fives, and sixes are worth +1.

When you see a card get dealt, you add its value to your running count.

When the count is positive, you bet more.

When the count is negative or zero, you bet less.

This system by itself is enough to get you to a point where the casino has no edge left over you, but there are a couple of other intricacies to consider.

The first is compensating for the number of decks in play. The more decks the casino is using, the less effect an individual card has on the odds. To compensate for this, you divide the running count by the number of decks you estimate are still left in the shoe.

This gives you the true count, which is what you use to determine your bet sizes.

The second wrinkle is deciding how much to bet. Most card counters use a betting range based on the size of their default bet. That default bet is a single betting unit. It could be $5, $10, $50, or some other amount.

For example, you might decide to have a conservative betting range of one to four units. If you’re a $5 bettor, you’d be betting $5, $10, $15, or $20 per hand, depending on the count.

Your default bet is $5, so you just add the true count to one to get the size of your bet.

If the count is +1, you’d add that to get 2 betting units. That’s $10.

If the count is +2, you’d be betting $15.

And if the count is +3, you’d bet $20.

There’s more to it than that if you want there to be, but that’s the basics of how to count cards in a nutshell.

Why Is It Illegal to Count Cards?

Here’s a shocker for you:

It’s not illegal to count cards.

Unless you’re using a computer or some kind of device, you can’t be arrested for counting cards because you’re not breaking any laws. If you think about it, it wouldn’t even make sense for counting cards to be illegal.

You’re just thinking strategically about the game as you’re playing.

Why would that be illegal?

But even though it’s legal, card counting is—to say the least—frowned upon by the casinos.

How Do Casinos Prevent Card Counting?

Casinos prevent card counting through various countermeasures. One of the easiest countermeasures for a casino to put in place is to use a continuous shuffling machine.

This creates a situation where you really are facing independent events on every hand. The cards that have been dealt are fed back into the shuffling machine, so their removal from the deck has no effect on the odds for the next hand.

Lowering and raising the size of your bets suddenly has no effect.


Even casinos which don’t use continuous shuffling machines decide when to shuffle the deck.

If they think a player is counting, they’ll start shuffling the deck more often to eliminate any potential advantage the card counter might have.

Those aren’t the only countermeasures used. If a casino suspects a player of counting cards, they’ll also back him off the game. They’ll ask him to stick with the other games in the casino.

They might even ask him to leave the casino and never return.


Coming back into a casino after you’ve been asked to leave is trespassing.

And even though counting cards isn’t illegal, trespassing is.

Who Are the Most Famous Card Counters?

The most famous card counters are the MIT Blackjack Team. Their exploits were detailed in a movie, 21, which was based on a book titled Bringing Down the House by Ben Mezrich.

The individuals who comprised the MIT Blackjack Team aren’t famous, though. One of the ways a card counter demonstrates how good he is involves staying anonymous.

After all, once you become famous, the casinos don’t want to play blackjack with you anymore.

Plenty of blackjack authors are what you might consider famous card counters, too, though.

This includes Ed Thorp, who’s considered the father of card counting, and Sanford Wong, who’s practically a legend in the card counting community.

How Much of a Bankroll Do You Need for Card Counting?

Card counting doesn’t guarantee you a winning hand or a winning session. It’s a long-term strategy that only works over thousands of hands. This means that you can run bad for quite a while before your long-term edge kicks in.

To keep from going broke, you need a large bankroll to withstand the deviation involved in any random game like blackjack while you’re waiting for your edge to kick in.

How big a bankroll?

It depends on how risk-averse you are.

If you’re willing to accept a higher probability of going broke, you can get by on a smaller bankroll. If you really want to minimize your probability of going broke, you need a larger bankroll.

Most card counters measure the size of their bankroll based on betting units, which we discussed earlier.

If you’re highly risk tolerant, you can get by with 200 units, but if you’re risk averse, you should probably strive for 1000 units instead.

If you’re a $5 bettor, your bankroll should be between $1,000 and $5,000.

Once you’ve doubled the size of your bankroll, you can move up in stakes.

Can You Count Cards at Online Casinos?

You cannot count cards at online casinos, not even online casinos with live dealers and real decks of cards. Here’s why:

Here’s why: Online casinos shuffle the deck after every hand.

And yes, even the online casinos with live dealers and real decks of cards do this.

The reshuffling of the deck results in a reset of the count to zero by the time you place your next bet, eliminating the ability to get an edge over the casino.

Conclusion

What is card counting in blackjack?

It’s just a means of getting an edge over the casino by tracking the relatively number of high cards versus low cards in the deck.

Why is card counting illegal?

It’s not. It’s just frowned on by the casinos. They’d love for you to believe that it’s illegal, though.