Every casino game, from a one-cent slot to a high-limit blackjack table, runs on the same simple idea: the rules are arranged so that the house keeps a small, predictable slice of every dollar wagered over the long run. Learn that one idea and the rest — odds, payouts, house edge, return to player (RTP), variance and the random number generator (RNG) — falls into place. This page is the starting point for our casino games guide for Canada: it explains the core maths in plain language and then points to the deeper explainers for each concept. Nothing here is a tip for winning, because no tip changes the built-in edge; the goal is simply to help you understand what is really happening when you play.
Key Points
- Every casino game has a house edge — payouts are set slightly below the true odds, so the house wins over time.
- House edge and RTP are the same thing seen from opposite sides and add up to 100% (a 4% edge = 96% RTP).
- The game you choose matters most: edges range from under 1% (blackjack, baccarat Banker) to 25–29% (keno).
- Volatility is not the edge — it describes how much results swing, not how much a game costs long-term.
- Results are random: an RNG decides each outcome independently, so nothing is ever “due.”
- No system beats the edge; the smartest move is choosing low-edge games and setting firm limits.
The one rule behind every casino game
Every casino game is built to pay winners slightly less than the true odds of their bet, and that gap is the casino’s profit. A game would be “fair” if winnings exactly matched the chance of winning. Casino games are deliberately not fair in that mathematical sense: the payout on a winning bet is always a little smaller than it “should” be. That small shortfall, repeated across millions of bets, is how a casino makes money while still letting individual players win on any given night.
This is why the honest framing matters: over time, every casino game favours the house. You can win in the short term — that is exactly what keeps games exciting — but the longer you play, the closer your results drift toward the built-in edge. Understanding the maths will not flip that edge in your favour; it will only help you choose games with better odds, manage your money and keep expectations realistic.
Odds vs. probability vs. payouts: what the words actually mean
Probability, odds and payout are three different things, and casinos profit from the gap between the last two. Keeping them straight is the foundation for everything else.
- Probability is the chance an event happens, usually written as a percentage or fraction. A single number on a European roulette wheel has a 1-in-37 chance of hitting — about 2.7%.
- Odds express the same chance as a ratio of ways-to-lose versus ways-to-win. For that single number, the true odds are 36 to 1 against.
- Payout is what the casino actually pays you when you win. On that same single-number roulette bet, the casino pays 35 to 1, not the true 36 to 1.
That one-unit difference between true odds (36 to 1) and the payout (35 to 1) is the entire source of the house’s advantage in roulette. Across every game, the pattern is identical: the true odds are one thing, the payout is slightly stingier, and the difference belongs to the house. When payouts match true odds, there is no edge; when they fall short, there is.
What is the house edge?
The house edge is the casino’s average profit expressed as a percentage of each bet you make. If a game has a 2.7% house edge, you can expect to lose, on average, 2.7 cents of every dollar you wager over the long run — not on any single bet, but averaged across a very large number of them. Wizard of Odds, a widely cited mathematical reference, defines it as “the ratio of the average loss to the initial bet.”
A worked example makes it concrete. Suppose you bet $5 a spin on European roulette for 200 spins, wagering $1,000 in total. At a 2.7% house edge, your expected loss is about $27. You might actually finish ahead or far behind on the night — that is variance, covered below — but $27 is the mathematical centre of gravity your results pull toward. The house edge is the single most useful number for comparing how expensive different games are to play.
What is RTP (return to player)?
RTP, or return to player, is simply the house edge turned inside out: it is the percentage of total wagers a game is designed to pay back to players over the long run. The two numbers always add up to 100%. A slot with a 96% RTP has a 4% house edge; a game with a 2.7% house edge has a 97.3% RTP. RTP is the term you will see most often on slots and online games, while “house edge” is more common for table games — but they describe the same thing from opposite directions.
Two cautions about RTP. First, it is a long-run statistical average calculated over millions of simulated rounds, not a promise about your next session; a 96% RTP slot can still take all your money in an hour or pay a jackpot on spin one. Second, RTP is sometimes adjustable: some slot titles ship with several RTP settings, and the operator chooses which to run, so the same game can return 96% at one casino and 94% at another.
House edge by game: a comparison
House edges vary enormously — from well under 1% on a well-played blackjack hand to roughly 25–29% on keno — so the game you choose matters far more than any betting system. The table below lists typical figures for the main casino games, verified against standard mathematical references. Treat them as representative ranges: exact numbers shift with specific rules, pay tables and bet types.
House Edge by Game
| Game / bet | Typical house edge | Notes |
|---|---|---|
| Blackjack (basic strategy) | ~0.5% (as low as ~0.3%) | Depends heavily on table rules and player decisions |
| Baccarat – Banker bet | 1.06% | Lowest main bet; commission applies on wins |
| Baccarat – Player bet | 1.24% | Slightly worse than Banker |
| Craps – Pass / Come line | 1.41% | Backing odds bets carry 0% edge |
| European roulette (single zero) | 2.70% | One zero on the wheel |
| Caribbean Stud Poker | ~5.22% | Table poker variant |
| American roulette (double zero) | 5.26% | Extra “00” nearly doubles the edge |
| Slot machines | ~2%–15% | Varies by title and RTP setting |
| Baccarat – Tie bet | ~14.4% | A classic high-edge side bet to avoid |
| Keno | ~25%–29% | Among the highest edges on the floor |
The headline takeaway: a few table games (blackjack with correct strategy, baccarat’s Banker bet, the craps Pass line) sit around 1% or lower, while side bets, proposition bets, big-wheel bets and keno are among the most expensive wagers on the floor. Choosing a low-edge main bet over a flashy side bet is the single biggest mathematical lever an ordinary player controls.
What is volatility (variance)?
Volatility — also called variance — describes how wildly a game’s results swing around its average, not how much it costs you over time. Two games can share the same house edge yet feel completely different. A low-volatility game pays small amounts often, so your balance drifts gently. A high-volatility game pays rarely but can pay big, so your balance lurches up and down.
Variance is why short sessions are so unpredictable even when the long-run maths is fixed. The house edge tells you the direction your money travels over thousands of bets; volatility tells you how bumpy the ride is in between. High-volatility slots and long-shot bets produce the dramatic wins people remember and share — and, far more often, the quiet losses they do not. Matching a game’s volatility to your bankroll and your tolerance for swings is a matter of comfort, not a way to beat the edge.
How randomness works: the RNG
Modern casino outcomes are decided by a random number generator (RNG), a computer algorithm that produces unpredictable results with no memory of what came before. Every slot spin, every shuffle in a digital card game and every electronic roulette result is generated independently: the machine does not know or care what happened on the previous spin, and past results have zero influence on future ones.
This has two important consequences. First, a slot is never “due” to pay after a cold streak, and a number is never “due” on the wheel — each event starts fresh. Second, fairness depends on the RNG being genuinely unpredictable and untampered, which is why licensed games are tested and certified by independent labs. A certified RNG does not remove the house edge; the edge lives in the pay table and payout rules, while the RNG only ensures each result is honestly random.
Common myths and mistakes
Most costly casino mistakes come from misunderstanding the maths above, not from bad luck. Clearing up the biggest ones protects your bankroll more than any “system” ever could.
- The gambler’s fallacy. Believing a result is “due” because it has not appeared recently — red after a run of blacks, a jackpot after a dry spell. Because each round is independent, the odds reset every time.
- Betting systems beat the edge. Doubling after losses (the Martingale) or other progressions rearrange when you win and lose but never change the house edge. They mainly increase the size of your eventual losing streak.
- Demo or “free” play improves your real odds. It does not. Practice mode runs the same maths; it only helps you learn the rules.
- Chasing losses. Increasing bets to “win it back” exposes more money to the same negative edge and is the fastest route to a large loss.
- Confusing a jackpot with good odds. A huge top prize usually comes with high volatility and often a lower RTP, not a better deal.
- Ignoring the bet type. Within one game, a good bet and a terrible bet can sit side by side — a 1.06% baccarat Banker bet next to a 14%+ Tie bet.
Which games give players the best odds?
The games with the lowest house edge — and therefore the best long-run odds for players — are blackjack played with correct basic strategy, baccarat’s Banker bet, and the Pass/Come line in craps, all around 1% or below. European (single-zero) roulette at 2.7% is clearly better than American (double-zero) roulette at 5.26% for the same style of bet. Slots range widely, so published RTP is the only reliable guide. Keno, big-wheel bets and most proposition and side bets sit at the expensive end and are best understood as entertainment, not value.
“Best odds” still means the house wins over time; it just means it wins more slowly, so your money and playing time last longer. No game on any casino floor offers a long-run edge to the player.
A quick glossary of casino maths terms
These are the core terms you will meet across every casino game explained on this site.
- House edge: the casino’s average long-run profit as a percentage of each bet.
- RTP (return to player): the percentage paid back to players over time; 100% minus the house edge.
- Probability: the chance of an outcome, as a percentage or fraction.
- Odds: the ratio of ways to lose versus ways to win.
- Payout: what the casino pays on a winning bet, usually slightly less than true odds.
- Volatility / variance: how much results swing around the average.
- RNG: the random number generator that decides outcomes independently.
- Expected value: the average result of a bet over the long run, which the house edge makes negative for the player.
Who this guide is for
This page is for anyone who wants to understand casino games before or instead of playing them — curious beginners, players who want to choose lower-cost games, and anyone trying to separate fact from casino folklore. If you take one thing from it, make it this: the house edge is real, permanent and built into the rules, so the smartest decisions a player makes are choosing low-edge games, understanding variance, and setting firm limits on time and money.
Responsible gambling and Canadian rules
This page is educational and neutral; it is not betting advice and not encouragement to gamble. Because every casino game carries a house edge, gambling always costs money on average over time and should be treated as paid entertainment, never as a way to make money or recover a loss.
In Canada, the legal gambling age is 19 in most provinces and territories, and 18 in Alberta, Manitoba and Quebec. If gambling stops being fun or starts causing harm, free, confidential help is available. In Ontario you can reach ConnexOntario any time at 1-866-531-2600, and the Responsible Gambling Council offers resources and tools for players across the country. Regulated Canadian operators also provide self-exclusion, deposit and session limits, and links to local support. Set a budget before you play, never chase losses, and walk away when your limit is reached.
Sources
Frequently asked questions (FAQ)
Do all casino games favour the house?
Yes. Every standard casino game is designed with a house edge, meaning the payouts on winning bets are slightly smaller than the true odds. You can win in the short term because of variance, but over many bets the results trend toward the casino’s built-in advantage. No game offers a long-run mathematical edge to the player.
What is the difference between house edge and RTP?
They are the same figure seen from opposite sides and always add up to 100%. House edge is the share of each bet the casino keeps on average; RTP (return to player) is the share paid back to players. A 4% house edge equals a 96% RTP. “House edge” is common for table games; “RTP” is common for slots and online games.
Can strategy or a betting system beat the house edge?
Correct strategy can lower the edge in skill-influenced games like blackjack, but it cannot turn it positive. Betting progressions such as the Martingale only change the pattern of wins and losses, not the underlying maths, and they tend to enlarge losing streaks. No system changes the long-run edge built into the rules.
Which casino game has the best odds?
Blackjack with correct basic strategy has one of the lowest house edges, often around 0.5% or less. Baccarat’s Banker bet (about 1.06%) and the craps Pass line (1.41%) are also strong, and European roulette (2.7%) beats American roulette (5.26%). Keno and most side and proposition bets have the worst odds.
Are online casino games and RNGs rigged?
Licensed games use a certified random number generator (RNG) that produces independent, unpredictable results, and independent labs test these systems for fairness. A fair RNG does not remove the house edge — the edge lives in the pay table — but it does ensure outcomes are genuinely random and not manipulated round to round.