House Edge Explained: How Casinos Make Their Money
Definition
The mathematical advantage a casino has over players in any given game, expressed as a percentage of each bet the casino expects to keep long-term.
Full Explanation
The house edge is the built-in mathematical advantage that ensures casinos profit over time. It is the complement of RTP — a game with 96% RTP has a 4% house edge. This means that for every $100 wagered, the casino expects to keep $4 on average.
Different games have vastly different house edges. Blackjack with basic strategy can have a house edge as low as 0.5%. American roulette has a house edge of 5.26%, while keno can exceed 25%. Understanding house edge helps you choose games where your money lasts longer.
The house edge does NOT mean you lose that percentage every spin — it's a long-term statistical average. You can win big or lose everything in a single session regardless of the house edge. It simply describes the mathematical expectation over millions of hands or spins.
Why It Matters
Selecting games with lower house edges is the single most effective legal strategy to extend your bankroll. A player who understands house edge can make informed decisions about where to play. For example, placing bets on the Pass Line in craps (1.41% house edge) is mathematically superior to playing American roulette (5.26%).
Real-World Example
You play 1,000 rounds of American roulette at $10 per spin, wagering $10,000 total. With a 5.26% house edge, you'd expect to lose approximately $526. Play the same $10,000 on blackjack with basic strategy (0.5% edge), and your expected loss drops to just $50.
Related Terms
RTP (Return to Player)
The percentage of all wagered money that a slot or casino game will pay back to players over time, typically calculated over millions of spins.
Volatility (Slot Variance)
A measure of risk in a slot game that describes how frequently it pays and the size of wins. High volatility = rare but large wins. Low volatility = frequent but smaller wins.
Variance
A statistical measure of how spread out outcomes are from the average. In gambling, high variance means results fluctuate wildly; low variance means results cluster near the expected return.
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