Single Deck Blackjack

So, you want to play a game of blackjack. You go into your favorite casino and can't figure out what type of game you want to play. A single deck one or a multiple deck one? You remember that we told you that single deck games are more favorable for the player. Well, now it's the time to show you exactly how the number of decks in the shoe actually influences your odds.

Here is a table with exact figures on how the number of decks used in the game influence a player that follows basic strategy. You will notice that the casino's edge will vary according to the number of decks.

As you can see the one deck game is indeed the most favorable for the player. You may have also notice that the casino's edge will increase rapidly at first but even out when 8 decks are used. The most important increase is when two decks of cards are used. Compared to a one deck game the casino gains a 0.33% advantage. By the time we get to the 6 deck games the house advantage is only 0.6%. The truth is that games that use more than 8 decks of cards offer the same house advantage of 0.6%. It is possible to use as many decks as you want, even 100, but the casinos will never do that because the advantage is the same as in an a 8 deck game.

Your chances of getting a blackjack are greater when only one deck of cards is used. How can this be if the percentages do not change from single deck games to multiple deck games? You must thing what will happen to the shoe if one card will be dealt out. In a single deck game that card will have a greater influence on the shoe than when 8 decks of cards are in the shoe.

In a single deck game your chances of being dealt an Ace and a ten valued card are greater. You have a 4 in 52 chance of getting an Ace as a first card. If you do get an Ace then you have a 16 in 51 chance to get a ten valued card since there are 16 ten valued cards in the deck. If you do a simple calculation you will see that your chances of getting an Ace and a ten valued card are 4/52 x 16/51 = 2.41%.

If you take into consideration that you have an equal chance of getting a ten valued card and an Ace, then your overall chances of getting a blackjack increase to 2 x 2.41 = 4.82%. Taking the calculations even further we will find out that in a single deck game you are likely to get a blackjack every 20.72 hands that are dealt to you.

Here you can look at a chart with your chances to get a blackjack in different game types. You will notice that as the number of decks increase, your chances of getting a blackjack decrease. Here's an interesting statistic that will convince you that single deck games are more favorable: your chances of getting a blackjack decrease by 98% when playing an 8 deck game compared to playing a single deck game.

Getting a black is great. But it is even better when only you get a blackjack and the dealer doesn't. Now we will discuss the second reason why casinos want to use more decks of cards.

When more decks of cards are used the dealer will have a smaller chance of duplicating a blackjack.

When you get a blackjack you will be paid at a ratio of 3-to-2. But if the dealer will also get a blackjack the bets will be pushed. You will get your initial bet back and you will not win anything. Getting more blackjacks are better for you and the more blackjacks you get the dealer's chances of also getting a blackjack decrease. The more times you get paid at a ratio of 3-to-2 the higher your overall winnings will be.

Compared to a single deck game in a 6 or 8 deck game the dealer's chances of getting a blackjack will decrease by 20% if the player will get a blackjack.

The explanation why this happens is quite simple. In a single deck game the chances of the dealer also getting a blackjack are small. After the Ace and the ten valued card from your hand have been dealt out there is still a large portion of cards other than Aces and ten valued cards in the deck. So the dealer will not be likely to get a blackjack too.

If the player has a blackjack the chances of the dealer also getting a blackjack are:

• Chances of the dealer drawing an Ace = 3/50
• Chances of the dealer getting a ten valued card = 15/49

Just do a little math and you will see what the odds of both the player and the dealer getting a blackjack are: (3/50 x 15/49) x 2 = 27.25. We have multiplied the dealer's ratios by two because he has a chance of getting an Ace and a ten valued card and also a chance to get a ten valued card and an Ace. So in conclusion every 27.25 hands you and the dealer may both get a blackjack.

In the next table you will see what the chances of you and the dealer both getting a blackjack are:

In a multiple deck game such as a 6 or 8 deck game you have a 20% chance of pushing a blackjack hand.

In multiple deck games you have slimmer chances of getting the card that you need. Single deck games are more favorable from this point of view. This is because in a single deck game that card will have a greater influence on the shoe than when 8 decks of cards are in the shoe.

Let's have a look at an example to understand this better. For example if you are playing a single deck game and you have a card total of 11 on your initial two cards and the dealer has a 5. In order to win all you need is to get a 10. Your chances of getting a ten are 16 / 49 = 32.6%. But when playing a 6 deck game your chances of getting a 10 will be 96 / 309= 31.7%. In a 6 deck game your chances of getting the card you need have decreased by 5%. After all these calculations we can reach only one conclusion. Single deck games are more favorable for the player.

Insurance bets are also influenced by the number of decks used in the game. More decks of cards mean a higher advantage for the house when it comes to insurance bets.

Whenever the dealer's face up card is an Ace you may buy insurance. The dealer will ask all the players at the table if they want to do so. Insurance costs half your initial wager, but if the dealer gets a Blackjack insurance pays 2-to-1. You just lose your initial wager. If the dealer doesn't get a Blackjack you lose your insurance and the game continues.

When calculating the dealer's advantage on an insurance bet for a single deck game we must first know that:

• Chances of the dealer getting a ten valued card = 16/51
• Chances of the dealer not getting a ten valued card = 35/51

All we have to do now is calculate the casino's advantage: (16/51 x 2) + (35/51 x -1) = -5.8%.
But what is the casino's advantage when playing a 6 deck game: (96/311 x 2) + (215/311 x -1) = -7.4%.

In conclusion, taking insurance is not advisable in a single deck game, but even more so in a 6 deck game.

Be careful when picking a type of blackjack to play. The number of decks used is only one rule that can be changed. There are several other rules that can be changed by the casinos. And they tend to do this very often. So if enough rules are changed a one deck game may end up being less favorable for the player than a 6 deck game.

These are the rules for a one deck game that favor the player:

• The dealer will stand on all 17's;
• Double down is allowed; Double down on a split hand is also allowed;
• Splitting and re-splitting is allowed.

When these rules are applied to a one deck game the player has an advantage of 0.13%. This advantage can be increased if the player follows basic strategy.

Removing or modifying any of those rules will lower the player's advantage. For example if the player will not be allowed to double down a split hand his advantage will drop to 0.01%. And if the dealer will be allowed to hit on soft 17's the player will lose all his advantage. The house will have an advantage of 0.18%. But the rule that increases the house advantage the most refers to blackjack payouts. This rule states that blackjack wins will be paid at a ratio of 1-to-1.

The next table will show you how changing different rules in single deck blackjack influences the house advantage:

DAS = Double on a split pair;
HIT 17 = Dealer will hit on soft 17;
RAS = Re-split Aces;
Stand 17 = Dealer will stand on soft 17;
LS = Late surrender.

It is always best to find a blackjack table that uses the rules that offer us the greatest advantage. A blackjack game played with one deck but where the dealer will hit on a soft 17 will still have better odds for us than a six or eight deck game. But a six deck game with a lot of favorable rules for the player will have a house edge as low as 0.26%. This is almost as good as playing a single deck game.

Single deck games are preferred over multiple deck games. This type of blackjack usually offers the highest advantage for the player and is the easiest to play according to basic strategy. But do not rush to a blackjack table just because it offers a single deck game. Check the rules first and make sure that not many unfavorable rules have been introduced.