Underneath "double zero roulette house edge" lies a single number: the share of each stake a game keeps on average, known as the house edge. At table games it follows straight from the rules. A change in one payout or one dealer rule moves it, sometimes by more than the gap between two whole games. Knowing which rules matter lets a player compare tables in a few seconds and see what an hour of play is likely to cost.
Roulette shows the effect of rules more plainly than any other game. A wheel with one green zero keeps about 2.7 percent of every bet, and adding a second zero raises that to about 5.3 percent without changing a single payout. Some tables with one zero return half of an even money bet when the ball lands on zero, which halves the edge on those bets. The layout looks alike in every version, so the number of zeros is worth checking before the first bet.
Blackjack played with sound strategy carries one of the lowest edges in a casino, often under one percent, and the rules decide exactly where it lands. A natural paid at six to five instead of three to two adds more than a full percentage point on its own. Fewer decks, the right to double after splitting and an offer of surrender each trim the edge slightly. A player who guesses instead of following basic strategy pays a multiple of the published figure.
In the rules of the table, which fix the edge before the first hand is dealt and usually take about a minute to read.
A natural paid six to five instead of three to two adds more than a full point, while fewer decks, doubling after splitting and surrender each trim the edge a little.
Machines with the same cards and rules can differ only in what a full house and a flush pay, and that gap alone can shift the return by two or three points.
Blackjack with sound strategy often keeps under one percent, the baccarat banker bet a little over one percent, a single zero wheel about 2.7 percent and a double zero wheel about 5.3 percent.
Expected cost is the edge applied to the total staked, so a fast online table dealing far more rounds per hour can cost more than a slower game with a larger edge.