How the Number of Decks affects the House Edge in Blackjack

Blackjack is one of the most popular casino games played the world over in both land-based and online casinos. As any blackjack player knows, each casino offers a variety of blackjack game variants, each with its own number of card decks, rules and conditions which can change the game rather considerably.

Sometimes these changes favour the players, but often they favour the house and can increase the casino's advantage rather significantly.

Here we'll take a look at the house edge in blackjack and how it is affected by the number of decks used in a particular blackjack game.

Blackjack House Edge

Although playing blackjack according to sound basic strategy will lower the house edge quite considerably in this game, it is important to still keep in mind that the house advantage will always be at play, putting you at a disadvantage no matter how slight it may be.

There are several factors that give casinos an edge of players but the primary one is that should a player bust on a hand they will always lose their wager regardless of how the dealer's hand plays out.

Nevertheless, blackjack is still considered to be a player friendly casino game offering one of the lowest house edges (sometimes lower than 1%) and highest payout odds when played according to strategy, making it a game of skill that very few can resist.

Number of Decks in Play

In the majority of blackjack games, the number of decks in play directly affects the house edge. Some blackjack games have a fixed number of decks as this will affect the rules in some game variants.

That being said though, a number of blackjack games can be played using differing numbers of decks, which can either increase or lower the house edge. As a general rule of the thumb the fewer decks used in a game, the lower the house edge and therefore the higher the payout percentage will be when using optimum strategy and vice versa.

Why the Number of Decks in Blackjack Matters

The number of decks used in a blackjack game affects the house advantage as this directly influences the player's odds of hitting a natural blackjack. When fewer decks are in play and a player is dealt a 10 value card as their first card, the probability of the second card being dealt being an Ace is higher, and this of course results in natural blackjack.

In addition, the chance of the dealer being dealt a natural blackjack against the player's natural blackjack decreases. These hands result in a tie or Push and the player's original wager will be returned to him/her.

The Actual Percentages

Let's examine a fixed set of rules and see how the house edge is altered as more decks are added to play.

The Rules:

  • Double on any two cards
  • Dealer hits on soft 17
  • Double after split is permitted
  • Re-splitting of up to 4 hands is allowed
  • No Surrender
  • No hitting on split aces
  • Player's initial wager is only lost when the dealer holds blackjack
  • A cut-card is in use

Below is a table that lists the house advantage corresponding to the number of decks in play when playing the game with the rules discussed above.

  • Single Deck Blackjack: 0.17%
  • Double Deck: 0.46%
  • Four Decks: 0.60%
  • Six Decks: 0.64%
  • Eight Decks: 0.66%

As you can see, the more decks in use, the higher the house edge. So when looking for a blackjack game, always keep this in mind and try to stick to the single deck blackjack where possible.