When you go out and check different casinos for blackjack tables you'll notice something quite peculiar. Most of the time, you'll find tables offering multiple deck blackjack instead of the single deck version. It may be a fact of life today that finding a single deck game is a rare occasion. These games may be hard to find but they are out there.
Back in the day, the standard blackjack game was played using only a single deck of cards. It's easy to find these games since the dealers will be dealing the cards from their hands instead from a shoe that contains more than one deck.
With the advent of card counting and the relative threat posed by card counters, casino operators became more fearful. Thus resulting in today's situation, most casinos offering multiple blackjack games. The initial intention was to ward off card counters, unfortunately the action taken by the operators didn't only affect card counters but regular players as well.
In a single deck game, regular players who use basic blackjack strategy gain around a 0.001 edge over the house. Unfortunately, all that changed when casinos started adding more decks into a game of blackjack. By simply adding one more deck to the standard single deck game the house was able to gain a 0.34 edge over the players. Imagine what edge the house has if they added more decks. An eight-deck blackjack game will have a 0.57 percent house edge.
Of course the casino can give back some of that edge. There are two ways that a casino can do that for players. First is to institute more positive rules (for the players), second is to play blackjack with less decks. One of the things that players can opt for when choosing a table to play on is to check out the house rules first before sitting on a table to play blackjack.
Remember that what makes up the remaining cards on the deck affects the chances of players in winning a hand. As more cards are dealt from the deck during the course of the game the better or worse are the players' chance of winning.
In single deck blackjack, if a player is dealt an ace and a five and the dealer's up card is a six, we can be sure that there are 16 cards in the deck are valued at ten. If we do the math, that sums up to a 32.7% probability of getting a card with a value of ten. That opportunity goes down for a multiple deck game. By playing with six decks your chances of getting a ten goes down to 31.1%.
These are your odds when comparing single deck blackjack with multiple deck blackjack games. The house edge is where these two part ways.