The 10 Worst Blackjack Mistakes You Can Make – And What to Do Instead

| June 25, 2019 12:00 am PDT
10 Common Blackjack Strategy Errors

If you’re going to write about the worst blackjack mistakes you can make, you should probably start by defining what a blackjack mistake is and what makes one such mistake worse than another.

A blackjack mistake, for the purpose of this post, is a deviation from basic strategy. Mathematically speaking, every possible decision in every possible situation in blackjack has an expected value. The play with the highest expected value is the correct play.

Any deviation from that (other than deviations based on counting cards) is a mistake.

How do you decide which mistakes are worse than others?

The biggest mistakes in blackjack basic strategy are the ones with the worst mathematical expectation.

Of course, some of these mistakes are so boneheaded that no one would ever make such a mistake. I’ve eliminated these mistakes from consideration.

Here’s an example.

You have a hard total of 20. If you hit this total, you’ll almost certainly bust. That’s a terrible expected value, but I don’t know any player foolish enough to make such a mistake.

With that understanding, here are ten of the worst possible basic strategy decisions you could make when playing blackjack.

1 – Playing at a 6:5 Table

Okay, so this isn’t exactly a basic strategy issue. This is more of a game selection issue.

In recent years, casinos have started offering blackjack games that pay 6 to 5 for a blackjack instead of 3 to 2. They often even try to act like this is a better deal for the player.

Some gamblers fall for this because 6 is more than 3.

But it’s a ratio.

  • A 3 to 2 ratio on a $100 bet means you get a $150 payout for a blackjack
  • A 6 to 5 ratio on a $100 bet means you get a $120 payout for a blackjack

It’s obvious which one is better, but what’s not obvious is the difference in odds for the player.

Casino games are measured by their house edge. The lower the house edge, the better the game is for the player.

The house edge for blackjack is usually between 0.5% and 1% depending on the rules variations in place.

The change in blackjack payouts adds 1.5% to the house edge.

Instead of losing an average of $1 per every $100 you bet, you’ll lose $2.50 for every $100 you bet — on average, over time.

What else is awful about this rule?

If you bet an amount that isn’t a multiple of $5, you only get the 6 to 5 payout on the amount divisible by 5. Any overage gets paid off at even money.

Suppose you bet $13 at a 6:5 blackjack table.

You’d get a 6:5 payout on the $10, which means you’d get $12.

Then you’d get even money on the other $3, for a total payout of $15 on a $12 bet.

This is also bad for the dealer.

Many gamblers place a $1 bet for the dealer as a means of tipping him. At a 3 to 2 table, the dealer wins $1.50 when you get a blackjack.

But the casino doesn’t have chips for small amounts like 10 cents and 20 cents, so they don’t get the $1.20 they SHOULD get on that $1 bet. They just get even money.

The biggest mistake you can make playing blackjack is playing at a 6:5 table.

Stay away from such tables. If those are the only games the casino offers, find another casino that offers a better blackjack game.

2 – Insurance

Unless you’re counting cards, taking insurance is a big-time negative expectation bet. It’s deceptive, though, because it makes it look like you’re going to at least break even.

Here’s how insurance works, and here’s how the math behind it works.

If the dealer has an ace showing, an optional side bet called “insurance” becomes available. The size of this bet is always the same — half of your original bet.

If the dealer has a 10 as her hole card, insurance pays off at 2 to 1, which makes up for losing your original bet. (When the dealer has a blackjack, you lose your bet immediately unless you also have a blackjack.)

This SOUNDS like a good deal, but let’s look at the odds that the dealer has a 10 in the hole.

You have 16 cards in the deck worth 10 — four each of the following cards: 10, jack, queen, and king.

This means you have 36 cards that AREN’T worth 10. Every other card in the deck has another value.

36 to 16 is the same as 9 to 4.

Let’s say you take insurance 13 times in a row and get statistically perfect results. And let’s say you bet $100 on insurance each time — just to make the math easier.

You’ll lose nine times and win four times. The nine times you lose, you’ll lose $900.

The four times you win, you’ll win $200 each time, which is a win of $800.

You’ve lost $100 over the 13 hands, which is an average of $7.69 per bet.

This means that the house edge for taking insurance is 7.69%, which is huge compared to the house edge on the other bets at the blackjack table.

If you follow correct basic strategy, the house edge is between 0.5% and 1% in blackjack.

Making a play with a house edge that’s worse than the house edge at the roulette table is one of the worst mistakes you can make at the blackjack table.

3 – Standing on a Hard 12 If the Dealer Shows a 2 or 3

When the dealer is showing a 2, 3, 4, 5, or 6, she’s more likely to go bust. As a result, the correct play is often to stand rather than hit. If you bust before the dealer does, you still lose — even though the dealer loses later in the hand.

In fact, if you have a hard total of 13 or higher, it’s always the right move to stand if the dealer has a 2, 3, 4, 5, or 6 showing. You want to give the dealer an opportunity to bust.

But with a hard total of 12, you’re better off hitting.

Sure, you have 16 cards in the deck which will bust your hand.

But there are 36 other cards in the deck which will improve your hand.

This mistake will cost you roughly $4.50 for every $100 you bet.

4 – Splitting 10s

It’s tempting to split 10s because a hand that starts with a single card valued at 10 is a good way to get started. It’s always a mistake, though, because a hard total of 20 is so good that the dealer will only rarely beat you. After all, she must have a 21 to win against a 20.

You’ll find a lot of blackjack players who will split 10s if the dealer has a 2, 3, 4, 5, or 6 showing. They’re hoping that the dealer will bust, and they want to get twice as much money in action.

But you’ll win more often with a total of 20 by such a huge margin over having two hands starting with a 10 that you’re better off standing on the hard total of 20.

This is a terrible mistake, by the way. A player who only splits when the dealer shows a 6 is losing $52.85 for every $100 they bet.

5 – Standing on a Hard 16 If the Dealer Shows an Ace

It hurts to hit a hard total of 16 because most of the time, you’ll bust.

But sometimes the smart move is still a losing move in the long run. It’s just a matter of losing LESS money than you would taking the other option.

Yes, you’re probably going to bust.

But if you don’t hit, the probability that the dealer is going to win if she has an ace showing is so great that you’ll lose more money in the long run.

You’ll almost always hit a 16 if the dealer has any card worth 7 or more.

It’s relatively unusual these days, but some casinos offer an option called “surrender.” This means you give up half your bet before the hand plays out.

If the option is available, you should surrender with a hard 16 if the dealer has a 9, 10, or an ace showing.

This mistake costs $14.94 for every $100 bet in this situation.

6 – Hitting a Pair of 4s If the Dealer Shows a 5 or 6

Some basic strategy tables suggest never splitting 4s, 5s, or 10s, but there’s an exception to that.

If the dealer has a 5 or 6, in most blackjack games, the best play is to split the 4s.

Most players want to hit here because you don’t risk busting a hard total of 8 no matter what the next card is.

If the dealer has a 5 or 6, though, she’s so likely to bust that it makes sense to split the 4s.

By splitting, you get more money into action, and you still can’t bust unless you hit too many times.

This one costs about $8.50 for every $100 you bet.

7 – Doubling Down on an 11 If the Dealer Shows an Ace

Doubling down on a total of 11 is usually the right move, but it’s not ALWAYS the right move.

If the dealer has an ace showing, you DON’T double down on 11.

Your hope with a total of 11 is that you’ll get a card worth 10. Since a relatively higher percentage of cards in the deck are 10s, this is often a good bet. You get twice as much money into action, and you have a high probability of winning.

But this strategy varies based on the rules at the casino.

  • In some casinos, a dealer must stand on soft 17
  • In others, the dealer must hit a soft 17
  • If the dealer hits a soft 17, you should double down
  • If the dealer stands on soft 17, you should just hit

Also, anytime you can find a table where the dealer must stand on soft 17, you should prefer that over other games. The odds are better for the player with that rules variation in effect.

This one will cost you $2.49 for every $100 you bet on it.

8 – Standing on Soft 18 If the Dealer Shows a 3, 4, 5, or 6

Most gamblers know that you should almost always stand on soft 18, but you don’t ALWAYS stand on soft 18.

If the dealer has a 3, 4, 5, or 6, she’s more likely to go bust (we already covered that).

But with a soft total of 18, it’s impossible for you to bust.

So you should double down here to get more money into action when the dealer does bust.

This is an easy mistake to avoid. And it’s an expensive mistake, too — if you only stand versus an 18, you’re going to lose an extra $10.13 for every $100 you bet.

9 – Hitting a Pair of 2s Instead of Splitting When the Dealer Shows a 7

It might seem counterintuitive, but a starting card of 2 is better for the player than you might think.

Hitting a 4 is an obvious play, but the correct move against a dealer 7 is to split the 2s to get more money into action.

If you make this mistake, you’re costing yourself $9.68 for every $100 you’re betting, on average, over time.

10 – Standing With a Soft 18 When the Dealer Shows a 9

It’s easy to understand why people would make this mistake. A total of 18 is a good total, and chances are, your hand isn’t going to improve.

But if the dealer has a 9, there’s a good chance she has a 19, in which case, your 18 won’t do anything but lose.

In this instance, the correct play is to hit.

If you stand in this situation, you’re costing yourself $8.37 per every $100 you bet.


Everyone talks about how blackjack offers great odds, but they often neglect to explain that if you’re making mistakes, the odds aren’t so great.

If you can avoid the ten mistakes listed in this post, you’ll probably be getting as close to the best possible odds as anyone could ask for, though.

Nonetheless, it’s always best to memorize basic strategy in its entirety.

After all, it’s not really that hard to do.

One final mistake to mention here applies if you like playing blackjack online. There are tons of casino sites on the internet, but they’re not all of the same standard, and some have very questionable reputations. Playing at the wrong sites can lead to a bad experience, so make sure you choose where to play at carefully.

We can help, as we’ve compiled a list of the best online casinos that are all reputable and trustworthy.



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