Games of Chance: Mastering Casino Game RTP and Variance for Smarter Play
- The Bonus Box
- Jul 21
- 11 min read
Ever wondered how online casinos manage to stay in business when so many people are winning? You're not alone! It's a question at the heart of every game of chance, whether you're spinning slots, placing bets on roulette, or strategizing at the blackjack table. These games are designed with a built-in advantage for the casino, known as the house edge.
This house edge is set by the specific rules and payout structures of each game. Over hundreds of thousands – even millions – of rounds, this statistical advantage ensures that the total money collected by the casino will, over time, exceed the total winnings paid out. The long-term statistics are simply in the casino's favor.
But here's the exciting part: your individual visit to an online casino typically involves only a few dozen or a few hundred game rounds. In this short timeframe, the long-term statistics don't have enough time to truly "show up." This means the outcome of your session is much more influenced by chance – or "luck," as many call it! It's this very chance that allows lucky players to win and, at least in the short term, "beat the statistics."
To increase your chances of being one of those lucky winners, it's incredibly important to understand two core characteristics of any game: Payout Ratio (RTP) and Variance (Volatility). Understanding Casino Game RTP and Variance is precisely what we'll focus on in this article. Let's dive in!
Dissecting Casino Game RTP and Variance
This section will help you decipher the two most vital statistics for any game of chance: Payout Ratio (RTP) and Volatility (Variance). Grasping these concepts is key to making more informed decisions about your gameplay.
Payout Ratio (RTP): Your Expected Return
The Payout Ratio, also widely known as Return to Player (RTP) or payout percentage, is a long-term statistical rate. It tells you the total money won by players, divided by the total money staked over a massive number of game rounds. Essentially, if a game has a 95% RTP, it means that for every €100 wagered, the game is designed to pay out €95 in winnings over its lifetime.
The opposite of RTP is the house edge. If a game's RTP is 95%, the house edge is 100% – 95% = 5%. This 5% is the statistical profit the casino expects to make over the long run.
Let's take a closer look at the RTPs of some popular games:
Payout Ratio of Roulette:
In European Roulette, if you bet on black, there are 18 black numbers out of 37 total numbers (including the single zero). The payout is 2 times your bet.
This gives European Roulette an RTP of approximately 97.3% (2 * 18 / 37). The house edge is then 2.7%. Interestingly, European Roulette is designed to have the same RTP for all types of bets (color, specific number, etc.).
Note: American Roulette has two zeros, which significantly worsens its RTP and gives the house a larger edge. One type of bet even has a different RTP from the rest! We go much deeper into this topic in our comprehensive article about Roulette Odds and Pay-Outs – be sure to check it out if you want to learn more about roulette! |
Blackjack RTP:
Blackjack rules can vary slightly between casinos, which means the RTP can differ. However, when played using basic blackjack strategy, the expected RTP is generally around 99.5%. This makes it one of the most player-friendly casino games. For an in-depth guide to this strategy, see our article on Mastering Blackjack Using Basic Strategy Charts.
In live and online blackjack, the actual RTP can fluctuate as cards are dealt from the shoe (the device holding the cards). The RTP can range between 95% and even over 100%, depending on which cards remain. This is what card counters exploit – they estimate the real-time RTP and bet higher when the odds are in their favor. Be aware, though, that casinos have ways to detect and prevent card counting.
Payout Percentage of Slot Machines:
The RTP of online slots usually falls between 92% and 99%. A slot machine's payout percentage is determined by the symbols on its virtual reels, its paytable, and other specific rules of the game.
If you are curious which slots have the highest RTP, or want to explore tips and strategies for playing, dive into Our Ultimate Guide to Playing Slots.
Variance (Volatility) of Games of Chance
To put it simply, the variance (also known as volatility) of a game tells you how quickly your bankroll is likely to change while you play:
Low Variance: When playing a game with low variance, you'll generally win smaller amounts quite often. Your bankroll will change quite evenly, though typically it will gradually decrease over time.
High Variance: In a high-variance game, you might experience many losing rounds, but when you do win, the payouts are much larger. These occasional big wins punctuate longer periods of smaller losses or even steady declines.
Variance can also be described by the statistical distribution of winnings as a multiple of your bet. For instance, betting on a color in roulette pays out 2x your bet, while betting on a single number pays 36x your bet – that's a huge difference in variance!
The variance of slots is a bit more complex. Since you can hit many different winning combinations with varying multipliers, it's not simple to describe slot variance with a single number. Game providers often use more general descriptions like "low," "medium," or "high" for their slot machines.
Note: We dive much deeper into how slot machines work, including their RTP and variance, in our article about the Ultimate Guide to Playing Slots. |
The variance of a game has a significant impact on your chances to walk away from a casino as a winner. Here's a general rule of thumb: "The higher the variance is, the better your short-term winning odds."
Easier to Hit Your Goal: In a high-variance game, it's easier to hit a single large win that satisfies your goal in just one or a few game rounds.
Less Re-Betting: More rounds end in a loss, which means you're less likely to re-bet your previous winnings. This, surprisingly, can have a positive impact on your overall expected return (as we'll see next!).
Bigger Wins with Smaller Bets: If you can win a higher multiple of your bet, you can stake less money to have a chance at winning a significant amount. This reduces the total sum of your bets and, consequently, your long-term losses.
To illustrate, imagine a game with zero variance and a 99% RTP. In this game, a €1 bet would always pay out exactly €0.99. The outcome of each round would be entirely predictable, and winning would be impossible. Of course, no one would want to play such a game, but it highlights that a high RTP isn't the only thing that matters; variance is crucial for the thrill of winning.
Expected Return of Your Betting System
It's vital to understand that a game's payout percentage (RTP) expresses the expected payout from a single game round. This is a common misconception!
Let's assume you bet €100 on roulette and win €1200. If you then continue playing and stake that €1200 in subsequent bets, the RTP of the game (e.g., 97.3% for European roulette) applies to each of those new bets separately. The expected statistical casino profit, in this case, would be (€100 + €1200) (100% - 97.3%) = €1300 2.7% = €35.1.
Note: If you keep playing with your previous winnings, you should statistically expect to lose more than the initial house edge percentage on your original stake. Most players place bets using their previous winnings again and again, effectively losing a portion of their money each time. |
If you want to be a smart player, you must distinguish between the RTP of the game (which applies only to a single game round) and the expected return of your betting system.
Your betting system is determined by how you play during your entire session at an online casino. This includes:
Your chosen game and its specific variant or settings.
The sizes of your bets.
Your personal decisions about when to stop playing (your "target" win or "stop loss").
It's difficult to calculate the RTP of a betting system for just one player. That's why extensive simulations (often with millions of players) are used to get reliable results. The expected return of a betting system can be broadly defined as the ratio of the overall winnings of players who managed to hit their "target" to the net losses of players who weren't as lucky.
Note: Be aware that some websites might incorrectly swap these two definitions. Their definition of game RTP might give a false impression that players statistically lose only a small fraction of their money (equal to the house edge). In reality, if players continuously place bets using their previous winnings, they will lose more over time. The RTP of a poor betting system can even drop far below 50%, even for a game like blackjack, which has a 99.5% game RTP! |
The optimal betting system is theoretically one that has the same RTP as the game played. To achieve this, you must avoid placing bets using money you've previously won. The easiest way to achieve this (in theory) is to stake your entire budget in one round, and then either walk away with your win or accept the loss. Roulette can be a good game for this extreme system, as you can choose various odds for your bet.
EXAMPLE: Let's assume you have €100 to play with and your goal is to walk away with €900. Placing your entire €100 on a square bet (covering 4 numbers) in roulette is almost the optimal strategy for maximizing the RTP of your betting system in this scenario. You will either leave the casino with a nice amount of money or without €100, but your chances of hitting that goal are significantly higher than making many small bets. The biggest disadvantage of this approach, of course, is that your play session will be extremely short. |
How Variance of the Game Influences the Expected Return of the Betting System
Now, let's see how game variance dramatically affects your betting system's expected return. Imagine two players, each starting with €100 at a casino, and both leave if their bankroll hits €500 or goes to zero.
Player X: Bets €10 on a single number in roulette (high variance).
Player Y: Bets on a color (red/black) in roulette (low variance).
After simulating a million sessions for each player, the results were striking:
Player X (high variance bet) left the casino as a winner in 14.8% of his attempts. His average winning bankroll was €648, and he played around 16 rounds on average. The RTP of his betting system was 95.19%.
Player Y (low variance bet) managed to win in only 5.15% of his attempts. His average winning bankroll was €500, and his overall betting system RTP was a mere 21.42%. On the other hand, Player Y enjoyed playing for a much longer time – an average of 274 rounds.
From this example, you can clearly see that the variance of the game significantly affects your chances to leave the casino as a winner. Player X's system had an RTP more than 4 times higher than Player Y's, even though both were playing the same game (roulette) with the same underlying game RTP!
How Bet Size Affects the RTP of a Betting System
The size of your individual bets also plays a crucial role in the overall payout ratio of your betting system, assuming your initial bankroll remains the same. The general rule is simple: The higher the size of your individual bets, the higher (usually) the RTP of your betting system.
Let's use roulette again to demonstrate this effect. Players start with €100 and leave if their bankroll reaches €500 or goes to zero. Both players bet on color (low variance).
Player A: Bets €20 in each round. Out of a million simulations, 10.9% managed to reach €500, resulting in a 48.68% RTP for their betting system, with an average of 84 rounds played.
Player B: Bets €5 in each round. Out of a million simulations, only 0.88% managed to win, with an average of 706 rounds played and a much lower RTP of 3.55%. If Player B wants to leave the casino with €500, they would need to win 80 more rounds than they lose – a very rare streak!
The statistics are clear: When placing low bets on a low-variance game, you may play for longer, but your odds of winning a satisfactory amount drop significantly.
On the opposite end of the variance spectrum is a combination of a high-variance game with high bets. Imagine Player Z, who starts with €100 and decides to go "all-in" on a single number in roulette (very high variance). Simulations show that out of a million Player Zs, 2.71% managed to win. Crucially, each of these winners left with a massive €3600, resulting in an incredible 97.4% RTP for their one-round betting system. Each Player Z played exactly one round.
The Recommended Roulette Betting System (for fun and winning chances)
A good betting system is a careful trade-off between your odds of a satisfactory win (and its size) and the duration of your stay in the casino.
If your goal is to have fun for a reasonable amount of time while also having a good chance of winning, our simulations suggest the following for roulette with a €100 budget:
Bet Size | Bet Type | % Players Who Won | Avg. Win Amount | System RTP (%) | Avg. Rounds Played |
€2 | Color | ≈0% | N/A | ≈0% | Very Long |
€20 | Color | 10.9% | €500 | 48.68% | 84 |
€10 | Number | 14.8% | €648 | 95.19% | 16 |
€2-€4 | Number | (Higher than color) | (Significant) | (Very High) | (Medium) |
As you can see from these types of simulations, a much higher variance from bets on a single number can easily "beat" strategies using significantly larger bets on low-variance options like colors, especially if your goal is a substantial win. Moreover, using high-variance bets with adequately small stakes can still prolong your stay. For example, betting small amounts like €2-€4 on your lucky number in roulette appears to be one of the best options for balancing fun and winning potential with a fixed bet type and size.
Note: This forms the basis for one of our roulette strategies. It's quite effective and simple, but we also came up with and simulated other strategies that might be even better for you, depending on your preferences. Make sure to check them out if you want to find other interesting ways to play roulette in our full guide to Roulette Odds and Pay-Outs |
Key Takeaways
Here are the most important things to remember from this deep dive into games of chance:
Payout percentage (RTP) of games applies only to a single game round. Your actual expected return (the RTP of your betting system) will be lower if you continuously re-bet your previous winnings.
You statistically lose on every bet. Therefore, making fewer bets (especially large, impactful ones) generally results in a smaller statistical profit for the casino relative to your initial budget.
The RTP of your betting system depends on the game's inherent RTP, the game's variance, the size of your individual bets, and your strategy for when to stop playing.
Variance is determined by the potential size of winnings as multiples of your bet. The higher the individual wins possible (for a fixed RTP), the higher the game's variance.
Games with high variance are usually more favorable for achieving a significant win in the short term. The advantage of significantly higher variance can easily outweigh the advantage of a slightly higher game RTP.
The higher the variance, the higher your chance of turning a small initial bankroll into a much larger sum.
The bigger your individual bets in one round (relative to your total bankroll), the higher the RTP of your betting system. This is because it reduces the number of total bets placed.
If you play for fun and want good odds of hitting a satisfactory win, look for games with high variance and consider placing smaller bets. A few big wins could get you to your desired target; otherwise, you'll lose your budget more quickly but with fewer overall bets. Remember, you're making a trade-off between how long you play and the ultimate return of your strategy.
Understanding these concepts empowers you to make smarter choices at the online casino. Which game characteristic do you find most surprising, RTP or Variance? Let us know in the comments!
Ready to Play Smarter? Think you're ready to put your knowledge to the test? Check out our recommended casino partners online casinos / crypto casinos and take your strategy for a spin!
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