What the house edge is
The house edge is the average share of each bet that the casino expects to keep over a very large number of bets. It is written as a percentage of the amount wagered. An edge of 1% means that, on average, the casino keeps 1 unit for every 100 units bet.
Two details matter. First, it is a long-run average, not a prediction for any one session. Second, it applies to the amount bet in total, not to the amount you bring to the table. If you place many small bets, the total wagered can be many times your starting stack.
Blackjack is a game of real decisions, so the edge is not one fixed number. It depends on the rules of the table and on how well the player’s decisions match the best available play. Every figure in this article is a rounded, typical value for illustration. A particular table can differ, and the only way to know is to check its rules.
Typical percentages
Under commonly described conditions, a player who follows basic strategy faces a house edge of roughly half a percent. That is often quoted as a rough reference for tables with fairly favourable rules. It is not a promise about any specific casino.
The edge rises when the rules get less favourable or when the player strays from the best play. A player who guesses, or follows hunches, typically faces a noticeably higher edge. It is common to see casual play described as costing a few times more than careful play, though the exact figure depends on how often and how badly decisions differ from the recommended ones.
Even with perfect play, the edge stays above zero in ordinary conditions. Strategy lowers the casino’s advantage but does not remove it.
What changes the edge
Several rules move the number, usually by fractions of a percentage point each:
- How naturals pay. Natural payouts of 3 to 2 are better for the player than 6 to 5. On a $10 bet a natural pays $15 at 3 to 2 and $12 at 6 to 5. About 4.8 hands in 100 start as a natural, so that $3 gap adds up to roughly $14 to $15 per 100 hands of $10, which is on the order of 1.4 to 1.5% of the money wagered. That is why 6 to 5 tables are widely regarded as a poor deal.
- Dealer behaviour on soft 17. Whether the dealer hits or stands on a soft seventeen changes the edge slightly. Hitting it is generally worse for the player.
- Number of decks. More decks typically add a small amount to the edge, so the number of decks is one of the rules worth noting.
- Doubling, splitting and surrender. Restrictions on doubling after a split, limits on resplitting and the absence of surrender each cost the player a little. A full list of how each rule shifts the edge belongs in a rule-by-rule table, and each effect is small by itself.
Because each rule is small but they stack, two tables that look alike can differ by a meaningful amount once all rules are added together.
What the edge means per 100 bets
The most practical way to read the edge is to multiply it by the amount you wager. A few illustrations, using round numbers:
| Edge | Bet size | Total wagered (100 bets) | Average expected loss |
|---|---|---|---|
| 0.5% | $10 | $1,000 | $5 |
| 1% | $10 | $1,000 | $10 |
| 2% | $10 | $1,000 | $20 |
| 2% | $25 | $2,500 | $50 |
Check the arithmetic with one row: 100 bets of $25 is $2,500 wagered, and 2% of $2,500 is $50. The same method works for any figures.
These are averages. Real results vary enormously around them, which is why a single hand or even a single evening says little about the edge. A player can finish a session ahead and the edge is still there; it simply has not caught up yet. The spread of results around the average is described by standard deviation, and the way averages settle down as bets accumulate is the law of large numbers at the table. Over a small number of hands, luck usually swamps the edge. Over a very large number, the average tends to dominate.
Common misreadings
“The edge means I lose that percentage of my stack.” It does not. It is a percentage of the total amount bet.
“A low edge means I will probably win.” A low edge still favours the casino. Most players will have winning and losing sessions, but over time the average tends toward a net loss.
“Past hands change the odds of the next one.” They do not in the way people expect. After a run of losses, the next hand is not “due” to win, and the edge on the next bet is the same as before. Chasing losses by raising bets does not change the average and can make losses much larger.
Using the number sensibly
Because the edge is a cost, it is more useful to treat it like a price than a puzzle to beat. Decide in advance what you are comfortable spending for the entertainment, using a session budget, and treat that money as already spent. Never bet more than you can afford to lose, never borrow to play, and do not try to win back losses.
Gambling can be harmful. If it is causing you or someone you know distress, consider contacting a local support service. The idea behind responsible gambling is simple: the maths is stacked against the player over time, so the decision to play should rest on what you are willing to pay for the experience, not on an expectation of profit.