# Why are single deck blackjack games better for the player?

September 12, 2013 Posted in Casino Games by No Comments

One timeless piece of blackjack advice that you’ll see in almost any strategy guide is to look for games with fewer decks. Single deck blackjack games are the best, followed by double deck games, triple deck games and so on. The fewer decks there are, the better it is for the player.

But why is this so? What’s the difference between a single deck of cards and 8 decks of cards? Surely they all have the same ratio of Aces, Faces and number cards. Don’t worry; you’re not the only person to wonder how this can be. I asked the same question when I first got started with blackjack.

With fewer decks in play, you are more likely to get blackjacks while the dealer is less likely to get blackjacks. It’s all about the ratios.

Your odds of drawing an Ace out of a single deck of cards are 4 out of 52, or 1 in 13. After you get that Ace, your odds of drawing a 10-value card next are 16 out of 51, or 1 in 3.1875.

Now, let’s look at that same calculation using 8 decks. Your odds of drawing an Ace out of 8 decks are 32 out of 416, or 1 in 13. Same as above. However, let’s look at the odds of drawing a 10-value card next. There are now 415 cards and 128 of those are ten-value cards. The odds your next card is a 10-value card are 1 in 3.24219.

You can see that the odds for getting a 10-card after an Ace got slightly worse this second time around. That’s because the removal of one card from the pool of available cards has less of an impact on 8 decks than it has on a single deck. The ratios are ever-so-slightly worse with more decks in play.

The above calculation only shows one way to get a blackjack. It’s also possible to get a 10-card first and then an Ace second. Let’s look at this in more detail.

Odds of a Blackjack in a Single Deck Game

Let’s find out how often you can expect to get a blackjack in a single deck game. There are two ways to get a blackjack:

1. Draw an Ace and then a 10-card

• Odds of drawing an Ace: 4 out of 52 or 1 in 13
• Odds of drawing a 10-card next: 16 out of 51 or 1 in 3.1875
• Now multiply these two results (1/13 x 16/51) and you get: 16/663 or 2.413%

Summary: You’ll get a blackjack in this manner 2.41% of the time

2. Draw a 10-card and then an Ace

• Odds of drawing a 10: 16 out of 52 or 1 in 3.25
• Odds of drawing an Ace next: 4 out of 51 or 1 in 12.75
• Now multiply these two results (16/52 x 4/51) and you get: 16/664 or 2.413%

Summary: You’ll get a blackjack in this manner 2.41% of the time

Now you add up both of these results for a grand total 4.826%. That is how often you’ll get a blackjack in a single deck game. This equates to roughly one blackjack in every 20.72 hands of play.

Odds of a Blackjack in an Eight Deck Game

Alright, let’s work through it all again with 8 decks in play.

1. Draw an Ace and then a 10-card

• Odds of drawing an Ace: 32 out of 416 or 1 in 13
• Odds of drawing a 10-card next: 128 out of 415 or 1 in 3.2422
• Now multiply these two results (1/13 x 128/415) and you get: 128/5395 or 2.373%

2. Draw a 10-card and then an Ace

• Odds of drawing a 10-card: 128 out of 416 or 1 in 3.25
• Odds of drawing an Ace next: 32 out of 415 or 1 in 12.969
• Now multiply these two results (128/416 x 32/415) and you get 128/5395 or 2.373%

Now you add up both of these results for a grand total of 4.746%. That is how often you’ll get a blackjack in an eight deck game. This equates to roughly one blackjack in every 21.1 hands.

What we see here is that you will get blackjacks slightly more often in single deck games than in eight deck games. The difference appears small, but there are a couple of things to keep in mind. Not only do you get blackjacks more often (which means more frequent wins), but you get paid more often for those wins. On top of that, the dealer is less likely to tie you with his own blackjacks in single deck games.

Blackjacks Pay More

And remember, you get a higher payout if you draw a natural 21. Instead of the normal even-money payout, you get a 3:2 payout. Combine that bonus payout with the increased likelihood of getting blackjacks in a single deck game and you get a lower house advantage with single deck games.

The Dealer Ties Less Often

It is always a letdown when you get a blackjack and then the dealer also gets a blackjack. If you run through the numbers from the dealer’s point of view, you’ll see that the dealer is less likely to tie you in a single deck game.

Double Down Situations are Better

Doubling down plays an important role in blackjack strategy. When you play blackjack with fewer decks, double down situations are more likely to end up in your favor. Let’s say you have 4-7 and the dealer is showing a 9. Let’s look at the odds of drawing a 10-card in a single deck game and in an eight deck game.

In both situations, you already know the values of three cards: your two cards and the dealer’s up-card. We won’t include those three cards in the following calculations because they are already known. We’re trying to figure out what will happen with the remaining unknown cards.

In a single deck game, this means there are 16 out of 49 cards that will help you. The odds of improving are therefore 32.65%.

In an eight deck game, this means there are 128 out of 413 cards that will help you. The odds of improving are therefore 30.99%.

Long story short, you are more likely to improve to a 21 when doubling down in single deck games than you are to improve in eight-deck games.

## Player Beware

Not all single deck blackjack games are good for the player. Single deck blackjack games are only better if the rules are the same. Many casinos offer single deck blackjack games but with changes to the rules that make single deck blackjack worse for the player.

One of the biggest offenders is 6:5 blackjack. This is a variant that changes the payouts for a blackjack from 3:2 to 6:5. In other words, the payout for blackjacks are significantly lower. This results in a higher house advantage.

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