House Edge in Blackjack Explained: Strategies, Rules & Odds for Better Play
Blackjack has a special status among the casino games: It is the only casino game that allows for a clear and efficient optimal strategy, which was the theoretical outcome of intensive academic work, and the game that offers players the best chances of beating the house. This last sentence should be understood not in terms of odds of winning, but of expectation and house edge. In this article you will see how these statistical notions apply in blackjack and how house edge varies with the blackjack strategy and variants.
- Expected value and house edge in blackjack
- How the house edge changes by strategy
- House Edge Without Optimal Strategy
- House Edge With Basic Strategy
- House Edge by Blackjack Variant
- House Edge Impact of Rule Variations
- Effect of Number of Decks on House Edge
- The adequate interpretation of the house edge in blackjack
- Conclusion
Expected value and house edge in blackjack
Like in any casino game, in blackjack you place a bet. That bet is that you will beat the dealer in that round and it has several payout rates, depending on the precise outcome (3/2, 1, 0, or –1 in classical blackjack).
By factoring in all the probabilities of the possible events and their associated payouts, we come to the expected value (or expectation) of that bet:
EV = (probability of winning) × (payoff if you win) + (probability of losing) × (loss if you lose), where the loss is quantified as a negative number.
As we know,
house edge is then HE = –EV. It reflects the percent that the house retains from the player’s wagers as their profit.
This general formula may look simple, but actually it is not in the case of blackjack, because it has to employ the entire tree of possibilities reflecting the progress and development of a round. This means that we have to take into account all player’s decisions, like standing/hitting, splitting, doubling, and surrender (if accepted).
Unlike roulette, for instance, where the possible final events (win or lose the initial bet) do not depend on previous events and as such the application of the above formula is straightforward, in blackjack there are intermediary stages of a round where the player can take various decisions, either strategic or random, influencing the final event. This is the reason why in roulette the house edge is fixed, while in blackjack it is relative to each player’s strategy.
The house edge in blackjack does vary not only with strategy, but also with the variants of the game. This is true because each version assumes either a new payout schedule (influencing the factors in the formula of the EV) or new rules (influencing the possible events and the number of factors), or both.
How the house edge changes by strategy
Blackjack allows optimal strategies. An optimal strategy is a mathematically conceived strategy (as a set of if-then-else rules) which maximizes the profit and minimizes the loss over the long run. In blackjack, there is the so called “basic” optimal strategy and the card-counting optimal strategy.
House Edge Without Optimal Strategy
For a player not using any optimal strategy (that is, using splitting, doubling, etc., but intuitively rather than following an optimization algorithm), the house edge in classical blackjack can be estimated to around 6%. More precisely, depending on the number of decks used:
| No. of decks | Expected value | House edge |
| 1 | −0.0574 | 5.74% |
| 2 | −0.0580 | 5.80% |
| 3 | −0.0579 | 5.79% |
| 4 | −0.0606 | 6.06% |
| 5 | −0.0583 | 5.83% |
| 6 | −0.0574 | 5.74% |
| 7 | −0.0588 | 5.88% |
| 8 | −0.0588 | 5.88% |
Such values are more than twice higher than the house edge of European roulette. Obviously, it would be a bad decision for a player not to use an optimal strategy in blackjack, given that this game allows it.
House Edge With Basic Strategy
If using the basic optimal strategy, the house edge in classical blackjack changes as follows:
| No. of decks | Expected value | House edge |
| 1 deck | −0.0017 | 0.17% |
| 2 decks | −0.0034 | 0.34% |
| 3 decks | −0.0044 | 0.44% |
| 4 decks | −0.0049 | 0.49% |
| 5 decks | −0.0053 | 0.53% |
| 6 decks | −0.0056 | 0.56% |
| 7 decks | −0.0059 | 0.59% |
| 8 decks | −0.0062 | 0.62% |
The house edge increases with more decks because of two effects: First, blackjack frequency decreases and the player blackjacks help more than dealer blackjacks hurt. More decks mean fewer naturals, which is worse for the player. Second, dealer’s informational advantage increases. Player acts first and busts lose immediately and larger decks reduce the effectiveness of composition-based decisions.
The house edge gets even lower with the card-counting optimal strategy, around 0.1%. Of course, you won’t find a lower house edge across casino games. However, to benefit of it requires a perfect play based on the skills associated with this optimal strategy, which are not at everybody’s hand.
House Edge by Blackjack Variant
The next table notes the house edges in the most popular variants of blackjack, played with one deck and with basic optimal strategy:
| Blackjack variant | House edge |
| Atlantic City Blackjack | 0.15% |
| American Blackjack (H17, no surrender) | 0.60% |
| Big Five Blackjack (6:5 BJ) | 1.85% |
| Classic Blackjack (favorable SD rules) | 0.13% |
| Double Exposure (dealer cards exposed, ties lose) | 0.70% |
| European Blackjack (ENHC, no surrender) | 0.50% |
| Pontoon (ENHC + bonuses) | 0.40% |
| Premier Blackjack (ENHC, limited options) | 0.42% |
| Spanish Blackjack (Spanish 21) | 0.38% |
| Super Fun 21 | 0.94% |
| Vegas Downtown Blackjack (SD, liberal rules) | 0.35% |
| Vegas Single Deck Blackjack | 0.35% |
| Vegas Strip Blackjack (SD, slightly tighter rules) | 0.38% |
House Edge Impact of Rule Variations
The next table notes the change of the house edge depending on the rule variation, relative to the house edge of classical blackjack:
| Rule variation | House edge change |
| Blackjack pays 6 to 5 | +1.39% |
| Dealers hits soft 17 | +0.22% |
| Double down on 10 or 11 only | +0.18% |
| Cannot double after splitting | +0.14% |
| European No Hole Card rule (ENHC) | +0.11% |
| Split up to two hands | +0.10% |
| Double down on 9, 10 or 11 only | +0.09% |
| No late surrender | +0.08% |
| Split up to three hands | +0.01% |
| Can resplit Aces | −0.08% |
| Double down rescue (surrender after doubling) | −0.10% |
| Hit or double down on split Aces | −0.19% |
| Double down on any number of cards | −0.23% |
| Player 21 wins straight away | −0.54% |
| Blackjack pays 2 to 1 | −2.27% |
Effect of Number of Decks on House Edge
The following table notes the house edge increase relative to one-deck game, depending on the number of decks used:
| No. of decks | House edge |
| 2 | +0.412% |
| 4 | +0.556% |
| 5 | +0.584% |
| 6 | +0.603% |
| 8 | +0.627% |
If the house edge is taken as the sole criterion of choosing among blackjack variants, the above tables offer sufficient information to use in your comparisons. It is clear that 3:2 blackjack is far more advantageous than 6:5 blackjack and the 2:1 blackjack offers the highest decrease in house edge (−2.27%). A 3:2 one-deck blackjack with any of the rules “Hit or double down on split Aces”, “Double down on any number of cards”, and “Player 21 wins straight away” is a choice that reduces the house edge of a classical blackjack game with one of the highest rates, with respect to rules.
The adequate interpretation of the house edge in blackjack
Once you’ve got the required skills for applying an optimal strategy in blackjack you can benefit of the lowest house edge across casino games. But what does this actually mean?
A lower house edge does not mean that your chances to beat the dealer’s hand increases, in one round or over a definite number of rounds.
Instead, it means that over the long run your loss is minimized and your profit is maximized with an overall result that is better than with other strategies or playing with no strategy, provided you play constantly with the same optimal strategy.
House edge is a statistical average (like expected value) and as such is a limit. The more rounds you play, your loss will approach the house edge. You may say that the lowest house edge, say 0.1%, still reflects an overall loss, so where is the gain?
However, minimization of the loss is one of the most important premises for winning in gambling, as it saves from your bankroll and gives you additional chances to win further, by playing more rounds. Playing by an optimal strategy in blackjack leads you to moments where the expected value is even positive, especially if using a card-counting strategy. It is a feature of blackjack not present in other casino games.
The condition for the house edge to materialize as a limit is for you to stick with the strategy you use, not changing it across the rounds, and applying it correctly.
Conclusion
Blackjack offers the lowest house edge across the casino games, with its minimal values reached when the player uses an optimal strategy. The house edge varies with the strategy, but also with the variants of the game (including the number of decks used).
Getting informed about the house edges associated with the blackjack variants helps you choose the game with the lowest house edge.
House edge does not apply in isolated rounds or in short- to medium-run, but only in the long run, provided you play constantly with the same strategy.
The statement that blackjack offers “the best odds” among the casino games should be meant only in terms of house edge; however, a low house edge also contributes to the strength of your bankroll and to the chances for future wins.