Home /
News /
Does The Number Of Decks Matter In Blackjack? /

Does The Number Of Decks Matter In Blackjack?

Many Blackjack professionals will tell you that playing with fewer decks of cards is better. But why should that be? Surely if you're playing with more decks, then the actual number of each rank of the card must remain proportionally the same. For example, no matter if we are playing with one or six card decks, the proportion of aces is always 1/13th. So does the number of decks matter?

Rate this news

You Get More Blackjacks in Games With Fewer Decks

The truth of the matter is that with a lesser number of decks you’ll receive more blackjacks. You’ll also do better on your double downs. Well, you may ask, how can that be if the proportion of ranks remains the same? It’s simply because removing cards has much more impact on a game with fewer decks. Let’s have a deeper look and examine the math…

Play BlackJack at the King Billy Casino

How Often Will You Draw a Blackjack From a Single Deck?

Now pay attention. In order to get the probability of drawing a blackjack from a single deck, we need to multiply the chances of drawing an Ace by the chance of drawing a 10 value card. Now in a single deck of cards, there are 4 Aces and 16 value 10 cards (4 x Ten, Jack, Queen, and King).

p(Ace) = 4/52 = 1/13
p(Ten) = 16/51

The difference lies in the removal of the Ace, and you can see this in the second line (51 cards).

Keep in mind that we should double our initial result as we could end up drawing either (10/Ace) or Ace/10). Our final result is:
p(Blackjack) = p(Ace) * p(Ten) * 2 = (1/13) * (16/51) * 2 = 4.83%

This means that the probability of drawing a blackjack from a single deck is 4.83%.

The Number of Decks: How Often Will You Draw a Blackjack From Two Decks

So let’s have a look at what happens with 2 decks. Let’s follow the same idea, but with different numbers. So we have 104 total cards, and these include 8 Aces and 32 ten-value cards.

p(Blackjack) = 8/104 * 32/103 * 2 = 4.78%.

So the probability of drawing a blackjack from two decks is 4.78%. That translates as the greater the number of decks, the less probability of drawing a blackjack. In 6 decks the probability drops down to 4.75%.

So a larger number of decks means slightly fewer blackjacks. In six decks, the probability drops further yet to 4.75%.

Double Downs Work Better in Fewer Decks Too

It’s exactly the same effect that has an impact on double downs. For example, if you double down your initial hand of (6.5) for a total of 11, then you’re slightly more likely to draw a face card to make up 21 provided that the game uses a lesser number of decks. We also take note that the dealer is also a beneficiary of these changes. On the other hand, do keep in mind that the player wins 3:2 for blackjack. The dealer only gets the even money. And for a good hand, which is double-downed, then the player stands to win the initial bet twice. In other words, if both the player and the dealer get more good hands, it’s the player that stands to gain more.

The Number of Decks: But You Get Fewer Pat 20s in Fewer Decks!

There are some negatives that come from playing with a lesser number of decks. And for the same reasons! Yes, that sounds nuts, but you’ll actually get fewer dealt hands of 20. So, once you take out the first ten-value card, that leaves only 15 tens left in the deck of 51 cards in your single deck. In a double-deck, your chances improve with 31 out of a total of 103 cards both at the online jackpot sites or at the casino tables.

The main take away here is that the number of decks does matter, so you should ideally play with fewer decks of cards.