Every casino game is designed to return less money than it takes in. That's not cynicism or some old wives tale — it's the engineering.
The mechanism is called the house edge. The house edge is a percentage that represents the casino's expected cut of every dollar wagered over a large enough sample. It's built into the rules of the game itself, which means it applies equally to every player (that's you, beginners, regulars, and card counters!).
No strategy eliminates it. No betting tool beats it. No lucky streak changes it long-term.
What does change (significantly, we might add) is the size of the edge depending on which game you play, and which bet within that game you place. This guide breaks down how casino odds and house edge work, why they differ across games, and what the numbers actually look like for the games most commonly played by Canadians.
What Is the House Edge?
The house edge is the mathematical advantage the casino holds over players on any given game or bet. It's expressed as a percentage of each wager. It describes the amount the casino expects to keep, on average, across a very large number of bets.
A house edge of 5% doesn't mean you lose 5% of your money every session. It means that over a statistically significant sample of bets, the casino retains an average of 5 cents for every dollar wagered. Short-term results can swing wildly in either direction — that variance is what makes individual sessions feel like gambling. The house edge is what makes the casino profitable across thousands of players and millions of bets.
The edge is different from the odds of winning a single bet. You can win any individual bet. The house edge only guarantees the casino's advantage over time and volume.
The house edge is calculated from the game rules, not from outcomes. It's determined before anyone places a bet. Hot streaks and cold streaks don't change it, they're just variance playing out within a structure that the casino designed.
Understanding RTP
The related concept is RTP (Return to Player) which is simply the complement of the house edge. A game with a 5% house edge has a 95% RTP. Both numbers describe the same thing from opposite angles: one tells you what the casino keeps, one tells you what players receive back, on average.
| Term | What it means |
|---|---|
| House Edge | The casino's expected profit as a % of total wagers. Lower is better for the player. |
| Return to Player (RTP) | The % of total wagers returned to players over time. The complement of house edge. RTP + house edge = 100%. |
| Variance / Volatility | How much results swing around the expected average. High variance = bigger swings; low variance = steadier results. Doesn't change the house edge. |
| Theoretical vs. Actual | The house edge is theoretical over large samples. Any individual session can produce any result regardless of the edge. |
How the House Edge Differs by Game
This is where informed players have a genuine advantage over uninformed ones. The range of house edges across casino games is enormous. Depending on the type of game you choose, you may see anything from under 0.5% with optimal play to over 40% on certain lottery-style games. Every dollar you wager carries a different expected cost depending on the game.
| Game | House Edge | Notes |
|---|---|---|
| Blackjack (basic strategy) | 0.5% – 0.8% | Lowest in the casino — but only at optimal play on every hand. Varies by rules variant (number of decks, dealer hits soft 17, etc.) |
| Video Poker (Jacks or Better, optimal) | 0.46% | Can be under 0.5% with perfect strategy. Like blackjack, the edge drops dramatically with correct play. |
| Baccarat (Banker bet) | 1.06% | One of the lowest house edges available. Player bet is 1.24%; Tie bet is 14.4% — avoid the tie. |
| Craps (Pass / Don't Pass) | 1.41% / 1.36% | Competitive edge on the core bets. Proposition bets in the centre of the table run far higher. |
| European Roulette | 2.7% | Single zero wheel. One of the more player-friendly table games at this edge. |
| American Roulette | 5.26% | Double zero (0 and 00). That one extra pocket nearly doubles the house edge vs. European. |
| Slots (online, Canadian average) | 3% – 8% | RTP typically 92–97%. Varies significantly by game title and platform. Licensed Ontario casinos must disclose RTP by game. |
| Keno | 20% – 40% | One of the worst player-odds games in the casino. Expect to retain 60–80 cents per dollar wagered over time. |
| Lottery (national averages) | ~50% | The worst expected-value gambling product available. The large jackpots make up a small fraction of total prize pools. |
The lesson from this table isn't that you should only play blackjack and baccarat. It's that walking into a casino, or logging in to an online platform, without knowing roughly where a game sits on this spectrum is handing money to the house that you didn't have to.
Roulette: One Pocket Makes All the Difference
Roulette is the clearest example of how a seemingly minor rule change produces a dramatically different mathematical outcome for the player.
A European roulette wheel has 37 pockets: numbers 1–36 and a single zero. The house edge across all standard bets is 2.7% — derived from the fact that the 36-to-1 true odds of hitting a single number are paid at 35-to-1.
An American roulette wheel adds a second zero (00), making 38 pockets. The payouts remain the same — 35-to-1 for a straight number — but now the true odds of hitting that number are 37-to-1. That extra pocket, and the unchanged payout, pushes the house edge to 5.26%.
For a player betting $25 per spin at 100 spins per hour, that difference amounts to roughly $6.75 per hour extra expected loss on an American wheel compared to European.
| Roulette Bet | House Edge (European / American) |
|---|---|
| Straight Up (single number) | 2.70% / 5.26% |
| Split (2 numbers) | 2.70% / 5.26% |
| Street (3 numbers) | 2.70% / 5.26% |
| Corner (4 numbers) | 2.70% / 5.26% |
| Six Line (6 numbers) | 2.70% / 5.26% |
| Column / Dozen (12 numbers) | 2.70% / 5.26% |
| Red/Black, Odd/Even, High/Low | 2.70% / 5.26% |
| Five-Number Bet (0,00,1,2,3) — American only | n/a / 7.89% — avoid |
All standard roulette bets carry the same house edge within a given wheel type. The Five-Number Bet on American roulette is the one exception — it's worse than all others at 7.89% and should be avoided. Use our roulette calculator to see exact payouts and probabilities for any bet type.
Blackjack: The Game Where Decisions Actually Matter
Blackjack is the casino game where player decisions have the greatest impact on the house edge. You can actually see this difference in the numbers.
With optimal blackjack strategy, the house edge in most blackjack variants sits between 0.5% and 0.8%. Without it — playing by instinct, doubling randomly, standing on hands where hitting is correct — that edge can climb to 2–4% or higher.
Basic strategy is simply the mathematically optimal play for every possible hand combination given the dealer's upcard. It's been solved computationally and is freely available. No casino has ever banned someone for using it at the table.
The 0.5%–0.8% figure assumes standard rules. Different rule configurations push the edge in either direction:
| Rule Variation | Effect on House Edge |
|---|---|
| Dealer stands on soft 17 (S17) | Better for player — reduces house edge by ~0.2% |
| Dealer hits soft 17 (H17) | Worse for player — common in many online variants |
| Blackjack pays 3:2 | Standard — best for the player |
| Blackjack pays 6:5 | Significantly worse for player — adds ~1.4% to house edge. Avoid. |
| Double Down on any two cards | Better for player vs. restricted doubling |
| Double after split allowed | Slightly better for player |
| Fewer decks (single / double deck) | Slightly better for player vs. 6–8 deck shoes |
| No resplitting Aces | Slightly worse for player |
The single most important rule to check before sitting down: does blackjack pay 3:2 or 6:5? The 6:5 variant is increasingly common in online and land-based casinos and adds over 1% to the house edge. It turns a below-1% game into something considerably less favourable. Always check before you play.
Slots: High Variance, Variable RTP
Slots are the highest-revenue product in both online and land-based casinos. They also have among the highest house edges of any table-adjacent game.
RTP on slots typically runs between 92% and 97% for online casino titles, meaning a house edge of 3%–8%. The advertised RTP is usually a theoretical long-run figure calculated over tens of millions of spins. Individual sessions, individual players, and even individual playing periods can deviate substantially from the theoretical average.
Unlike blackjack or roulette, player decisions in slots don't affect the house edge. There's no optimal strategy. The main variables under player control are bet size and session length — both of which affect how quickly the house edge plays out against your bankroll, not whether it does.
What to Look For in Slot RTPs: Ontario's iGaming regulation requires licensed operators to publish per-game RTP figures — use this. It's one of the few consumer protections in the Canadian online casino space worth taking advantage of. RTP above 96% is generally considered good for a slot. Below 94% is on the unfavourable end. RTP percentages on slots are set by the game developer and are verified by independent testing labs before a game is certified for play. They are not adjustable by individual casinos. A Pragmatic Play slot runs the same RTP whether it's on one platform or another.
Keno: The Honest Truth About the Numbers
Keno is worth discussing separately because the gap between how it's perceived and what the maths actually shows is wider here than almost anywhere else in the casino.
The house edge on keno typically runs between 20% and 40%. For context: this means for every dollar wagered on keno, the casino expects to retain 20 to 40 cents. That compares to less than 3 cents on European roulette and less than 1 cent on well-played blackjack.
| Keno Format | Approximate House Edge |
|---|---|
| Casino keno (standard) | 25% – 40% |
| Ontario Daily Keno | ~30% |
| Keno Atlantic | ~30% |
| BC Keno | ~25% – 35% |
| National lottery keno variants | Can exceed 40% |
The wide range within keno comes from the number of spots picked and the specific paytable. Different casino operators and lottery corporations set their own prize structures. Use our keno number generator for random picks, and keep the house edge figure in mind when deciding how much to spend per draw.
Baccarat and Craps: The Underrated Low-Edge Games
Two games that don't get nearly enough attention from players looking for better odds:
Baccarat
Baccarat has a reputation as a high-roller game, but it's mechanically very simple. You bet on Banker, Player, or Tie, and the cards are dealt automatically according to fixed rules. No decisions required after placing your bet.
The Banker bet carries a house edge of 1.06% (after the standard 5% commission on Banker wins). The Player bet is 1.24%. Both are competitive. The Tie bet (which pays 8:1 or 9:1) looks attractive but carries a house edge of 14.4%. Avoid the Tie.
One simple rule for baccarat: bet Banker almost always. The maths is clear. The commission exists precisely because Banker wins slightly more often than Player, and the casino needs to account for that.
Craps
Craps has a complex-looking layout that puts many players off. But the core bets are among the most player-friendly in the casino. The Pass Line and Don't Pass bets carry a house edge of 1.41% and 1.36%, respectively. Better still: taking Odds behind the Pass Line (once a point is established) is a zero-house-edge bet. The casino pays true odds on the Odds bet. It's the closest thing to an even-money proposition in any casino.
The proposition bets in the centre of the table (including Hardways, Any Seven, Any Craps) run from 9% to over 16%. The layout is designed to draw attention to exactly these bets. The core bets are on the outer edges. Now you know where to look.
The Gambler's Fallacy and Why It Costs Money
The house edge is a long-run mathematical constant. It doesn't accelerate or decelerate based on recent results. And yet one of the most persistent and expensive beliefs in gambling is that recent outcomes influence future probability.
It's called the Gambler's Fallacy: the belief that after a run of one outcome, the other is 'due'. "Red has come up seven times in a row on roulette… black must be coming." Or "A slot hasn't paid out in a while… it's due a hit."
Neither of these is true. Every spin on a roulette wheel is an independent event. The wheel has no memory. The previous seven reds have no effect whatsoever on the eighth spin. The same logic applies to slots, keno draws, and dice. Each outcome is statistically independent. 'Due' is not a real concept in random processes.
This matters practically because chasing 'due' outcomes leads to longer sessions, higher stakes, and more exposure to the house edge. That is the exact opposite of informed play.
Putting It Together: A Practical Summary
- Choose European roulette over American whenever possible.
- Play blackjack with basic strategy — it's not cheating, it's just correct play.
- Check slot RTPs before you play. In Ontario, licensed platforms are required to publish these.
- In baccarat, bet Banker. Commission included, it's still the better bet.
- In craps, stick to Pass/Don't Pass, and take Odds when available.
- Know the keno house edge going in. It's entertainment, not a strategy.
- Avoid: the American roulette Five-Number bet, the baccarat Tie bet, keno on a serious budget, and 6:5 blackjack.
None of this eliminates the house edge. Nothing does — and that's the point. But choosing a 1% game over a 25% game, and making correct decisions within that game, is the difference between treating your entertainment budget with respect and handing it over faster than necessary.
Understand More About How Betting Works
How Betting Odds Work
Formats, implied probability, and how sportsbooks build their margin into every line.
Read the Guide →How Parlays Work
Combined odds, compounding risk, and why the house edge multiplies across legs.
Read the Guide →Frequently Asked Questions
What is the house edge in simple terms?
The house edge is the percentage of each wager the casino expects to retain over a large number of bets. A 5% house edge means that for every $100 wagered across thousands of bets, the casino expects to keep $5 on average. Individual sessions swing in both directions — the house edge is a long-run mathematical constant, not a per-session guarantee.
Which casino game has the lowest house edge?
Blackjack with correct basic strategy has the lowest house edge of any mainstream casino game — typically 0.5% to 0.8% depending on the specific rules. Video poker with optimal strategy can get below 0.5% on certain pay tables. Baccarat (Banker bet) at 1.06% and craps (Pass Line) at 1.41% are competitive alternatives that require no complex strategy.
What is the difference between house edge and RTP?
They're two expressions of the same thing from opposite angles. A game with a 5% house edge has a 95% RTP (Return to Player). House edge represents what the casino keeps; RTP represents what players receive back. RTP + House Edge = 100%.
Does European roulette really have a better house edge than American?
Yes, significantly. European roulette has one zero pocket and a house edge of 2.70%. American roulette adds a second zero (00), producing a house edge of 5.26%. On all standard bets, American roulette costs the player nearly double. When both versions are available — which they almost always are at online casinos — choose European. Use our roulette calculator to compare payouts and house edge across bet types.
Can basic strategy really reduce the blackjack house edge to under 1%?
Yes. Basic strategy is the mathematically optimal play for every possible blackjack hand given the dealer's upcard. It's been solved computationally and extensively validated. With standard rules (3:2 blackjack, dealer stands on soft 17, double on any two cards), the house edge drops to roughly 0.5%. Without it — playing by intuition or hunches — players routinely face edges of 2–4% or more.
What is the house edge on slots?
Online slots typically have a house edge between 3% and 8% (RTP of 92%–97%). This varies significantly by game — some titles are above 97% RTP, some below 93%. In Ontario, licensed platforms are required to publish per-game RTP figures, which gives players better information than most jurisdictions offer. The RTP is set by the game developer and applies identically across all platforms running that title.
Why does keno have such a high house edge?
Keno's high house edge (typically 20%–40%) is partly structural and partly by design. The game offers large potential payouts on long-shot outcomes, and the prize pool is calibrated to ensure operator profitability across all betting patterns. Unlike blackjack, there are no player decisions that affect the edge — it's entirely determined by the paytable and number pool. Keno is a legitimate form of entertainment, but it's important to understand what the expected cost per session actually is.
Does the Gambler's Fallacy actually affect how people bet?
Substantially. Research on betting behaviour consistently shows that players adjust their bets based on recent outcomes — increasing stakes after losses ('it's due to turn') or after wins ('I'm on a run'). Neither pattern has mathematical basis. Every spin, hand, and draw is statistically independent. Past results don't affect future probability in any random process. Understanding this doesn't make sessions less enjoyable — it prevents some of the most expensive mistakes players make.
Where can I find the RTP for a specific slot game?
Most slot developers publish RTP figures in the game's information or paytable section. In Ontario, regulated online casino platforms are required to disclose per-game RTPs. If you're playing on a licensed Canadian platform and can't find the RTP, the platform's customer support is required to provide it.
Is there any casino game where the player has no disadvantage?
The Odds bet in craps, taken behind a Pass Line or Come bet once a point is established, pays at true odds with zero house edge. It's the only bet in any mainstream casino game where the house holds no mathematical advantage. The catch: it's only available after you've already placed a bet with a house edge (the Pass Line at 1.41%). But taking maximum odds behind that bet reduces the combined edge of your total craps position to well below 1%.