It’s hard to imagine that any casino table game will ever match the popularity of blackjack.

And you’d think, since the game is so perennially popular, that everyone would (by now) know the difference between good blackjack strategies, bad blackjack strategies, and terrible blackjack strategies.

But there’s only one correct way to play blackjack. Always use basic strategy. (I’ll leave a discussion of card counting and other advantage play techniques for another time.)

### What’s Basic Strategy?

You can buy a card in the gift shop of any major casino offering a correct (or mostly correct) basic strategy for blackjack. These cards are organized according to the possible totals in your hand, cross-referenced with the possible face-up cards that the dealer might have. Look up your total on the left, look across to the appropriate face-up card from the dealer, and the card gives you the decision with the best mathematical outcome.

You’d be surprised how many people ignore the basic strategy even when it’s freely available. Below I’ve listed the 7 biggest mistakes I’ve seen at the tables, along with why they’re terrible strategies. I also offer you advice about what you should do instead.

### 1- Taking Insurance

The correct strategy for insurance, if you’re not counting cards, is to NEVER take insurance.

Here’s why:

The insurance bet only LOOKS like a good bet. Most players are confused about it, though. Insurance isn’t part of your original bet. It’s a separate bet with a high house edge.

Here’s how insurance works:

When the dealer has an ace as her up-card, you can take what’s called an insurance bet. This bet pays off at 2 to 1 if the dealer has an 10 in the hole. (If the dealer has a blackjack, everyone at the table loses immediately–unless a player also has a blackjack, in which case it’s a “push”, or tie.)

The insurance bet must be half of your original bet. If you started with a bet of $100, the insurance bet would need to be $50.

One of 2 things happens:

- The dealer has a 10 in the hole. In this case, you lose your original bet of $100. But you win $100 on your $50 insurance bet.
- The dealer doesn’t have a 10 in the hole. In this case, you lose your $50 insurance bet immediately, but the rest of the hand plays out normally.

Insurance looks like a bet that will make you break even if and when the dealer has a blackjack.

Here’s an example from one of my recent playing sessions:

I bet $100. I got a 10 and a 7, for a total of 17. The dealer had an ace showing.

For purposes of this post–I needed an example to write about–I took the $50 insurance bet.

The dealer had a 10 in the hole. She collected my $100 bet, but she paid off $100 on my insurance bet.

The insurance bet is a sucker bet for 2 reasons:

- It’s a separate bet from your initial bet, and it has to be treated as such.
- The number of cards that make it a winner are fewer than the number of cards that make it a loser.

Let me speak to that 2nd point:

You’ll win the insurance bet if the dealer has a 10 in the hole. How many 10s are in the deck?

There are 16 of them–the 10s, jacks, queens, and kings are each worth 10 points.

But how many cards have a value other than 10?

36 of them.

If you know much about odds, you’ll recognize that the odds of winning the insurance bet are 9 to 4. (You have 9 ways to lose and only 4 ways to win.)

The payoff for this bet is 2 to 1 (or 8 to 4).

The house gets its edge from the difference between 9 to 4 odds and 8 to 4 odds.

How big is the house edge?

Let’s look at how you would calculate it.

Let’s assume you have 13 mathematically perfect hands at $100 each. You’d lose that bet 9 times for a loss of $900. You’d win that bet 4 times, for winnings of $800. You’d see a net loss of $100.

Average that over 13 hands, and you’ve lost $7.69 per hand. That’s a house edge of 7.69% on that bet.

The overall house edge at blackjack is between 0.5% and 1% if you’re using correct basic strategy. You shouldn’t be taking bets at the blackjack table with a house edge of between 7 and 15 times the normal house edge.

That’s mathematically indefensible.

### 2- Any Betting System that Isn’t Related to Card Counting

A betting system is a method of raising or lowering bets based on how you did on the previous hand. There are positive and negative betting progressions. None of these systems work in the long run.

The only betting system that works is card counting. When you count cards, you raise your bets when there are a lot of 10s and aces in the deck relative to other cards. You have a better chance of getting a blackjack, which pays off at 3 to 2, and this is what gets you an edge when counting cards.

Here’s how other betting progressions work:

In a positive progression betting system, you raise the size of your bets after you win. The goal is to catch a winning streak and maximize the amount of money you win from that streak.

Here’s an example:

You bet $100 on a hand of blackjack and win. You double your bet on the next hand. You win again, so now you have a net win of $300.

You combine this strategy with a win goal. This goal might be to win twice in a row or 3 times in a row.

If you lose at any point in the system, you go back to your original single-unit bet and stay there until you have another win.

You combine this with an overall win goal for your session. Most people also have a loss limit. A win goal is an amount of money you want to win. When you’ve won it, you quit playing. A loss limit is the amount of money you’re willing to lose in a session. Once you’ve lost that amount, you quit playing.

Another popular type of betting system is the negative progression system. The most popular example of a negative progression system is The Martingale. It might sound obvious at this point, but in a negative progression system, you raise your bets after losing.

Here’s an example of The Martingale System in action:

You bet $100 on a hand of blackjack and win. You add the winnings to your stack of winnings.

You then bet $100 on the next hand and lose. In a negative progression system, you raise the size of your bets when you’re losing. With the Martingale, you double the size of your bet. This time you’ll bet $200.

The idea is that you’ll recoup your losses and show a small profit–because after all, how many times in a row can you realistically expect to lose?

The problem with negative progression systems like The Martingale is that they assume that long losing streaks are less common than they are.

Let’s take a look at how quickly your next bet will get really large with a sample progression starting with a $10 bet:

- $10
- $20
- $40
- $80
- $160
- $320
- $640
- $1280

It might seem unthinkable that you’d lose 8 bets in a row, but it happens.

What happens with The Martingale System is that you’ll have many sessions where you win a small amount of money.

But eventually, the chickens are bound to come home to roost. When that happens, you’ll suffer a devastating loss or 2. And those losses will be big enough that you’ll lose all your winnings and then some.

### 3- Copying the Dealer

Some blackjack players assume that because the house has an edge in blackjack, you can eliminate that edge by following the same strategy as the dealer.

If you know much about blackjack, you know that the dealer has specific rules about how she has to play each hand. She can’t use her judgment to decide what to do.

Usually those rules are pretty simple. She always hits a total of 16 or less and always stands on a total of 17 or more.

If you follow that strategy, you’re giving up a tremendous amount of house edge to the casino. For one thing, you eliminate all the possible profits from splitting and doubling down. Players who copy the dealer’s strategy never splits and never doubles down, because those are options unavailable to the dealer.

Also, mathematically, the best decision in some situations varies based on what kind of card the dealer has showing.

Here’s an example:

If you have a hard total of 16, you should stand if the dealer has a 2, 3, 4, 5, or 6 showing. That’s because the dealer has a greater chance than usual to bust.

If you were copying the dealer’s strategy, you would hit a 16 every time.

What would happen to the house edge if you just copied the dealer’s strategy on every hand?

It would skyrocket. The house edge is normally between 0.5% and 1%. But start copying the dealer and ignore the basic strategy, and you’re facing a house edge of 8% instead of 1%.

### A Note about the House Edge

What exactly is the house edge, and why does it matter?

The house edge is a mathematical prediction of how much money you’ll lose on average per bet. It’s expressed as a percentage.

It’s important to remember that the house edge is a long-term expectation. In the short run, you’ll see results that vary wildly from the house edge.

Here’s an example, though:

You’re playing blackjack for $20 per hand, and you’re seeing an average of 70 hands per hour. That’s $1400 per hour you’re putting into action.

The casino expects, over enough players and enough hands, to win at least 1% of that. (They actually expect to win more, because most blackjack players don’t follow basic strategy.)

This means your expected hourly loss is $14/hour.

Adjust that number to 8%, which is what the house edge would be if you’re copying the dealer’s strategy.

Now you’re expected hourly loss is $112/hour.

That’s a huge difference. You’re still losing money, but you’re losing money at a dramatically different rate.

Think about it in terms of a cost for a certain amount of entertainment. You might be willing to pay $14 to play blackjack for an hour. You might even be willing to pay $14 to see a movie.

Are you willing to pay $112 to see the same movie?

Are you also willing to pay an average of $112 per hour for that game of blackjack?

### 4- Doubling Down on Every Total of 9, 10, or 11

Some new blackjack players never double down. When they first learn about how doubling down works, they often start doubling down every time they have a total of 9, 10, or 11.

This is often the right strategy, but any strategy in blackjack that doesn’t account for the dealer’s face-up card is a flawed strategy.

The only hand you’ll ALWAYS double down on is a total of 11.

You’ll ALMOST always double down on a total of 1o. There’s only one exception–if the dealer has an ace showing, you don’t double down. You just take another card.

With a total of 9, you’ll often double down, but not always. You’ll double down if the dealer has a 3, 4, 5, or 6. If the dealer has any other card showing (2, 7, 8, 9, 10, or A), you’ll just hit.

This is the mathematically correct play.

There’s no reason to give the house any more of a mathematical advantage than they already have.

### Finally

Blackjack is the most popular of all casino table games for multiple reasons. For one thing, it offers the best odds in the casino. It’s also a game that rewards skillful strategic play.

But to take advantage of those great odds, you have to put in the effort to use good blackjack strategies, NOT bad blackjack strategies.

As you can see, there are plenty of bad blackjack strategies available to choose from. And trust me, this post didn’t list all of them. I just stuck with the worst and most common terrible blackjack strategies.

Elsewhere on this site you can find details about the correct basic strategy to use on every hand of blackjack.