Effects of Number of Decks on House Edge in Blackjack

In a game of blackjack, the shoe is the contraption that holds all of the cards. A shoe can contain anywhere from one standard 52-card deck, to 8 full decks of cards. From a very basic point of view, it would seem that the number of cards in a shoe would have no real effect on the game. Each deck contains the same cards. No matter how many there are, the probabilities of receiving one card over another should be the same, right? Not so.

The fewer decks being used, the more likely it is for a player to be dealt a natural blackjack. In turn, when the player receives a natural blackjack, it is less likely that the dealer will also receive a natural blackjack, which would negate the traditional 3 to 2 payout for the player.

Because of this simple fact, the house edge in most blackjack variations becomes decreasingly lower with each deck eliminated from the shoe. Thus the best blackjack games, in general, are single-deck blackjack variants, while the worst house edge comes from 8 decks in the shoe. Any game of 4 decks or higher is essentially a bad choice.

In the same token, it is not just the number of decks in the shoe that affect the house edge. Just because you find a single-deck blackjack game in a live or online casino is no reason for joyful jumping. The rest of the rule variations will also have a direct impression on the ultimate house edge of the blackjack game.

If the right assembly of rules were to be introduced, a single-deck blackjack game could actually turn the tides so much that the player has the advantage. Of course, we can’t expect any casino operator to be so negligent as to present such rules. No casino is in the business of losing, and they certainly don’t count on the majority of their players being frivolous enough to play without a basic strategy, thereby voiding the opportunity to walk away a winner more often than not.

The best house edge you can expect to find is about 0.12% to 0.17%. For obvious reasons, the 0.17% house edge is easier to find. In order to achieve this rate, you would need to find a blackjack game with these common rules applied:

• Dealer Hits Soft 17
• Double on Any Two Cards
• Double After Split Allowed
• Split up to Four Hands
• No Splitting of Aces
• No Surrender (Early or Late)
• Player Always Loses to Dealer Blackjack

The rules above would create the following house edge according to the number of decks in the shoe.

• Single Deck = 0.17% House Edge
• Two Decks = 0.46% House Edge
• Four Decks = 0.60% House Edge
• Six Decks = 0.64% House Edge
• Eight Decks = 0.66% House Edge

If we change some of the rules above, we can get an even better house edge. Simply allowing the player to split aces would decrease the percentage by 0.18%. If the player could draw to split aces, the house edge would drop even further, 0.19%. But alas, by the chart above, this would create a player edge, thus other rules would have to be changed to bring the edge back into the casinos favor, often including the addition of decks in the blackjack shoe.