What Is the House Edge?
The house edge is the casino's built-in mathematical advantage on every game it offers, expressed as a percentage of each bet. It represents the average amount the casino expects to retain from every euro wagered over a very large number of plays. A house edge of 2.7% on European roulette means the casino expects to keep €2.70 of every €100 wagered in aggregate. This is not random — it is a mathematical certainty built into the game's design. The house edge is why casinos are profitable businesses. No amount of luck, skill (on pure chance games), or betting strategy eliminates it. The house always wins in the long run — that is not a cliché, it is the mathematical foundation of every game you play.
House Edge by Game Type
| Game | House Edge | RTP | Condition |
|---|---|---|---|
| Blackjack | ~0.5% | ~99.5% | Basic strategy; varies by rule set |
| Baccarat (banker) | ~1.06% | ~98.9% | After 5% commission on winning banker bets |
| European Roulette | 2.7% | 97.3% | Single zero; fixed by game structure |
| Slots (online) | 3%–6% | 94%–97% | Varies by title; check the info screen |
| American Roulette | 5.26% | 94.74% | Double zero; materially worse than European |
| Keno | 20%–40% | 60%–80% | Among the worst value games available |
The numbers above are verified mathematical figures for the stated conditions. For blackjack, "basic strategy" means the optimal play for every hand given the dealer's upcard — a published table you can memorise or reference. Without it, the house edge on blackjack rises to roughly 2–4% depending on play quality. The difference between European and American roulette (2.7% vs 5.26%) is simply the extra zero slot on the American wheel — always choose European if given the option.
Why You Can't Beat the House Edge
Betting systems are popular — the Martingale (double your bet after every loss), the Fibonacci, the D'Alembert — but they all share the same fundamental flaw: they rearrange the distribution of outcomes but cannot change the mathematical expectation. In a game with a 2.7% house edge, you are losing an average of 2.7% of everything you wager, regardless of how you structure your bets. The Martingale, for example, produces many small wins and rare catastrophic losses — the total amount won and lost remains aligned with the house edge. No betting system, no "hot streak" logic, no "due number" on roulette changes this. Each spin of the wheel or pull of the slot is statistically independent. Past results have no bearing on future ones. The only honest advice: treat casino games as entertainment with a known cost, not as a way to generate income.
House Edge vs RTP: Two Sides of the Same Coin
House edge and RTP (Return to Player) are the same relationship expressed differently. RTP is from the player's perspective: what percentage is returned. House edge is from the casino's perspective: what percentage is kept. They always add up to 100%. A 97% RTP slot has a 3% house edge. A 2.7% house-edge roulette table has a 97.3% RTP. When comparing games, you can use either figure — just remember they're opposite sides of the same number. See our full Casino RTP Guide for typical figures by game and how to find published RTPs.
Bankroll Management Given the House Edge
Knowing the house edge doesn't let you beat it, but it does help you manage your budget intelligently. A few practical principles: choose games with lower house edges (blackjack with basic strategy costs you less per hour than slots, in mathematical terms, all else equal); set a session budget before you start and treat it as the cost of your entertainment, not money you expect to get back; avoid side bets — most side bets in table games carry a much higher house edge than the main game; and understand that longer play means the edge compounds — the more you wager in total, the more the house edge extracts. Casino games are designed to be entertaining. Play them for the experience with money you can afford to lose. If gambling is becoming a problem: Gambling Awareness Trust, 1800 753 753, gamblingcare.ie. 18+ only.
Frequently Asked Questions
The house edge is the casino's mathematical advantage, expressed as a percentage of each bet. It represents the average amount the casino retains per euro wagered over a large number of plays. A 2.7% edge means €2.70 kept per €100 wagered in aggregate.
Blackjack with basic strategy has approximately 0.5% house edge. Baccarat (banker bet) is ~1.06%. European roulette is 2.7%. These figures assume correct play for skill-based games.
No. No betting system or strategy eliminates the house edge. Progressive systems like the Martingale change the shape of session results but not the mathematical expectation. The house edge guarantees a casino profit over sufficient play. Individual players can win short-term through variance, but no system beats the edge long-term.
Online slot house edges typically range from 3% to 6% (RTPs 94%–97%). This varies by title — check the game's info screen for the specific RTP. It is set by the provider and certified by independent labs.
They are the same relationship expressed differently. House edge is what the casino keeps; RTP is what players receive back. They always sum to 100%. A 96% RTP equals a 4% house edge.