RTP and House Edge — The Math Behind Every Casino Game

Return to Player is the percentage of total wagers a game returns to players over a very large sample. House edge is the remainder. A 96% RTP slot has a 4% house edge; a blackjack game with a 0.5% edge has a 99.5% RTP. They are the same fact stated from opposite ends.

The crucial detail is that both apply to total amount wagered, not to your deposit. Wagering 100 twenty times means 2,000 in turnover, and a 4% edge on that is an expected 80 cost — far more than 4% of what you brought.

Expected loss equals bet size times rounds per hour times house edge. A slot at 1 per spin, 600 spins per hour and a 4% edge costs about 24 an hour on average. Blackjack at 10 per hand, 80 hands per hour and a 0.5% edge costs about 4 an hour.

That calculation is the single most useful tool in this guide. It converts an abstract percentage into a budget you can plan around, and it explains why bet size and game speed matter as much as the edge itself.

Variance describes how far real results scatter around the average. High variance is why a player can win big on a 4% edge game in one session, and why another loses a full bankroll on a 0.5% edge game. Neither outcome contradicts the mathematics.

The house edge only becomes visible over tens of thousands of rounds. Casinos are guaranteed profit not because any individual loses, but because they run millions of rounds. You do not, which is exactly why short-run results feel random and long-run results do not.

Approximate house edges: blackjack with basic strategy 0.5%, baccarat banker 1.06%, baccarat player 1.24%, French roulette even-money 1.35%, European roulette 2.7%, craps pass line 1.41%, American roulette 5.26%, slots 3-6%, game shows 3-8%, keno 20-30%, baccarat tie 14.4%.

Poker sits outside this list entirely. There is no house edge — the operator takes a rake from the pot and players compete against each other, which is why a skilled player can be long-run profitable in poker and cannot be in any game on this list.

Progression systems change bet size based on previous results. Because each round is independent and carries the same edge, the sum of negative-expectation bets is negative regardless of their order or size. Martingale simply trades many small wins for one catastrophic loss.

The only real decisions available to you are which game to play, which bet within it, how fast to play and how much to stake. Those four choices control your cost per hour. Nothing controls the edge.