What Is the House Edge?
The house edge is the mathematical advantage a casino holds over players on any given game. It's expressed as a percentage of each bet that the casino expects to retain over the long run. It doesn't mean you'll lose that percentage every session — individual results vary widely — but it defines the mathematical reality of sustained play.
For example, a game with a 5% house edge means the casino expects to keep £5 for every £100 wagered over a very large sample of bets. Short-term results can differ dramatically from this expectation.
How the House Edge Is Built In
Casinos don't need to cheat. The edge is engineered into the rules of each game. Common mechanisms include:
- Payouts below true odds — A bet that has a 1-in-37 chance of winning (single number roulette) pays 35:1, not 36:1
- Rule asymmetries — In blackjack, the dealer wins if both player and dealer bust
- RTP settings on slots — A 96% RTP means a built-in 4% house edge
House Edge by Game Type
| Game | Approx. House Edge | Notes |
|---|---|---|
| Blackjack (Basic Strategy) | ~0.5% | Lowest edge when played correctly |
| Baccarat (Banker bet) | ~1.06% | Simple, low-edge option |
| Craps (Pass Line) | ~1.41% | Good odds on basic bets |
| European Roulette | ~2.7% | Single zero is player-friendly |
| American Roulette | ~5.26% | Double zero increases edge significantly |
| Online Slots | 2%–10%+ | Varies widely by game |
| Keno | 20%–35% | Very high house edge |
The Difference Between House Edge and Variance
Two games can have the same house edge but feel entirely different to play. Variance (or volatility) describes how wildly results swing around the average. A high-variance game might let you win big or lose quickly; a low-variance game produces steadier, smaller results.
Understanding both together gives a much clearer picture of a game's character than either metric alone.
How the House Edge Compounds Over Time
The house edge is applied to every bet placed — not just your starting bankroll. This is why time and number of bets matter so much. Playing faster, placing more bets, or choosing higher-edge games all accelerate the mathematical effect of the house advantage.
- Slower games (blackjack, roulette) give you more time per pound wagered
- Fast-paced slots can process hundreds of spins per hour, increasing total wagering quickly
Can the House Edge Be Reduced?
Yes — to a degree. Strategy plays a meaningful role in skill-influenced games:
- Blackjack — Using basic strategy (the mathematically optimal play for every hand) brings the house edge close to 0.5%. Deviating from it raises the edge considerably.
- Video Poker — Optimal hold strategy on certain variants can result in very competitive RTPs.
- Choosing the right bets — In craps, the pass line bet has a far lower edge than proposition bets.
For pure chance games like slots and roulette, strategy cannot change the house edge — but choosing games wisely (e.g., European over American roulette) still matters.
Key Takeaway
The house edge is not a conspiracy — it's the economic model that keeps casinos operating. Understanding it helps you make smarter game choices, manage your expectations honestly, and focus on entertainment value rather than profit expectations.