The house edge: where the casino's profit comes from
One rule generates the casino's entire profit at blackjack, and most of the other rules are partial refunds. Understanding the ledger tells you which tables to avoid.
The asymmetry that pays for the casino
Blackjack looks symmetrical: you and the dealer draw cards toward 21 under similar pressures. The profit hides in the order of play. You act first, and if you bust, you lose immediately, even if the dealer goes on to bust the same round. Both sides break roughly as often as each other over time, but only one side pays for it on the spot. That double-bust rule is essentially the entire house edge. Everything else in the rules is compensation flowing back toward you.
What you get in return
The 3:2 blackjack payout is the largest refund: you and the dealer are dealt naturals equally often, but only yours pays a premium. Doubling and splitting are the second: the dealer can never raise the stakes, and every double or split the chart recommends is a spot where the extra money has positive expectation. Late surrender returns a final sliver by capping your worst hands at half a loss. Add the refunds up against the double-bust cost and, under the rules on this site, about half a percent of disadvantage remains for a perfect player. Fifty cents per hundred wagered is among the smallest edges in the casino.
How rules move the number
Every rule variation is a repricing of that half percent. A table that pays blackjack 6:5 instead of 3:2 takes back about 1.4% all by itself, roughly quadrupling the edge; it is the single most expensive sign on a casino floor. The dealer hitting soft 17 costs you about 0.2%, which you can watch reshape the recommendations by flipping the setting in the analyzer. Removing doubling after splits costs about 0.14%, removing surrender about 0.08%, and moving from six decks toward one refunds up to about half a percent. Reading the placard before sitting down is worth more than memorizing the last ten cells of the chart.
The edge you choose yourself
All of the numbers above assume perfect basic strategy. Casual play, guessing at stiffs, skipping doubles, standing on soft 17, typically hands over 2 to 4%. The gap between those figures is the practical point of this entire site: rule selection and correct play together decide whether an evening costs you a coffee or a dinner.
What half a percent means in money
Expected loss is edge times total money wagered, and the wagering adds up faster than intuition suggests. At around 60 hands per hour betting 10 units, a perfect player at a 3:2 table expects to lose about 3 units per hour; the same player at a 6:5 table about 12; a casual player at that 6:5 table around 20 or more. Any single session can land anywhere, because variance in blackjack dwarfs the edge. The edge is simply the average all those sessions drift toward, and no play, bet pattern or hunch moves it. Only rules and strategy do.