Blackjack has one of the lowest house edges of any casino game—but it could be lower. The number of playing card decks that get shuffled together at a given blackjack table can radically change the gameplay.
In both blackjack online and in-person, the number of decks in play can vary, and raise or lower the house edge. Learn more about why casinos use different numbers of decks and how many decks are beneficial to players.
Why Casinos Switch Up the Number of Decks
The point of using playing cards in casino table games is that they provide random variance. If more cards are added, such as by shuffling multiple decks together while setting up blackjack games, that variance increases.
Casinos make their money based on mathematical probability, spread out over the course of millions of play sessions and countless players at slot machines and card game tables. These probabilities always average out in the long run, and casinos make sure the average is slightly in their favour so they make a profit.
Increased variance from more card decks helps even out the probabilities in blackjack. This creates a more level playing field, which benefits the casino. Because of this, more decks in play raise the house edge, while fewer decks lower the house edge to the advantage of the players.
How to Tell How Many Decks Are Used in Blackjack
At an in-person casino, the easiest way to determine the number of decks is to ask the dealer or a floorman keeping an eye on things. Stay relaxed and casual so they don’t think you’re trying to count cards. There’s no rule against asking!
The process is even easier when playing blackjack games online. Simply check the info section or the settings tab within the game, where payouts and RTP are listed. This info will include the number of simulated decks used at the digital card table.
Blackjack Odds by Number of Decks
There are several types of blackjack available in casinos. Games using only a couple of decks are rarer as they offer the highest odds to players. But games with half a dozen or more decks are most common.
Here’s a summary of how different numbers of decks affect the odds and payouts in blackjack:
- Single deck: 0.16% house edge
- Double-deck: 0.19%-0.36% house edge, depending on the rules
- Four deck: 0.60% house edge
- Six deck: 0.64% house edge
- Eight deck: 0.66% house edge
The above stats are based on traditional blackjack rules. Blackjack variants with extra game mechanics like side bets will also affect the odds. House edge figures vary depending on specific table rules such as whether the dealer hits or stands on soft 17, and whether doubling after splitting is permitted.
What is the Optimal Number of Blackjack Decks?
When scoping out a blackjack title, single-deck blackjack offers the best odds for players, sitting at 99.84% Return To Player (RTP). However, as noted above, the house edge is rule-dependent.
Because of the high odds, single-deck blackjack is somewhat rare. But particularly in the case of how online blackjack works, single-deck titles are especially advantageous. Online blackjack typically shuffles the entire deck after each hand, so multi-deck games are incredibly random, which mathematically benefits the casino. Single-deck titles reduce this randomness.
Multi-Deck Blackjack Strategy
Most blackjack games use six or eight decks, so it’s worth understanding the best blackjack strategies for multi-deck titles.
These tips are applicable to any blackjack title. The priority should be to have fun and treat gambling as a form of entertainment. Playing for profit can be dangerous; play for the love of the game.
Use a Strategy Chart
Blackjack has been around long enough that expert players have effectively “solved” the game. Strategy charts are widely available online. These offer instructions on when to hit, stand, double-down, or split to remove any element of guesswork.
Strategy charts generally aren’t accepted at in-person casinos, but they’re perfect for online casinos. Simply keep a chart open in another browser tab, on another monitor, or on a mobile device for quick reference.
Skip Card Counting
Card counting gets a lot of hype, but it can be a one-way ticket to getting banned from big casinos. Although counting cards isn’t illegal, casinos prohibit it as a house rule and instruct staff to watch for card counters. It’s very difficult to count cards without giving it away, so don’t even attempt it.
As well, blackjack played with multiple decks can overwhelm card counters by giving them too many cards to keep track of.
Bet and Budget Responsibly
To truly leverage the math underpinning blackjack, bet in small increments and try to extend each play session. The best results come from averaging out plenty of wins and losses over a long period of time.
This requires careful budgeting to avoid overspending. Chasing losses is a common mistake. Stick to a set bet amount. Small bets will also minimize risk to sidestep problematic gambling habits.
