House edge is the casino's expected mathematical advantage per unit wagered. A slot with 96% RTP has a 4% house edge — for every £100 staked across a very large sample, the casino expects to keep £4. Different games carry vastly different house edges: blackjack with optimal strategy can be below 1%, classic European roulette is 2.7%, American roulette is 5.26%, slots typically 2-8%, side bets often 5-15%.
House edge is a long-run statistical expectation, not a session guarantee. Short-term variance dominates individual sessions and players can win or lose far more than the house edge would predict in any given hour.
Example usage
- European roulette 2.7%
- Blackjack with strategy <1%
- Slots 2-8%
Related terms
- RNG (Random Number Generator) — The certified random-number generator that determines slot, table and instant-game outcomes — independently audited.
- RTP (Return to Player) — The long-run percentage of stakes a slot pays back to players over millions of spins.
- Side bet — An optional secondary wager on a casino game, typically with a higher house edge than the main bet.
- Volatility — How frequently and in what size a slot tends to pay out — high volatility means rare big hits.