If you are new to the game of blackjack you may not have noticed that some blackjack games are played with one deck of cards while others are played with 2, 4, 6 or even more decks of cards. What's the difference between single and multi-deck games and what are the advantages or disadvantages?
At one time, single-deck blackjack was the standard. However, casinos have swayed towards multi-deck games to make it harder for players to count cards, a strategy which has taken the blackjack world by thunder. Not only is it more difficult for players to count cards with multiple decks in use, but using multiple decks also increases the house edge slightly.
Many casinos have reintroduced the single-deck blackjack game, but don't be fooled into thinking that playing a single-deck game will give you better odds. In fact, you will notice that when playing a single-deck game of blackjack many casinos only offer a 6:5 payout for blackjack, while multi-deck games offer 3:2. If you placed a $10 bet and got blackjack on a multi-card game with 3:2 payout you'd walk away with $15, whereas you'd only get $12 for a single-deck game with a 6:5 payout. The slight increase in the house edge in a multi-player game isn't worth the decrease in payout that the house gives for a single-deck game.
Casinos also often enforce rule variations on single-deck and double-deck games in order to give the house more of an edge. These variations can include requiring the dealer to hit on soft 17, not allowing players to double down after a split and a number of other variations.
Even if you are a card counter, you can still count cards when using multiple decks, though it can be slightly harder than counting cards in a single deck. Therefore, unless you can find a casino that offers a 3:2 payout for single-deck blackjack it is a wise decision to stick to multi-deck games.