Slots RTP and Volatility Explained
The outcome of a casino game will always statistically favour the house. However, by getting a solid understanding of the two fundamental aspects that dictate how often and how much can win in any given game, you can increase your chances of winning.
Learn About RTP Percentages and Variance
In this article, we will explain Return to Player (RTP) and slots volatility - the two concepts that affect the outcome and winning frequency of a slot machine game. Moreover, we will also reveal how you can use betting strategies to manipulate these two aspects so that you win as much as possible.
It is no secret casino games are designed to give the casino an advantage in the long run - if they were not, there would not be any casinos around.
However, despite the numbers favouring the house, players always have a statistical chance of walking away as winners – and it is this unpredictable nature that plays into the risk versus reward psychology and drives people to gambling.
The reality is that a casino's advantage is calculated on an infinite number of game rounds. In other words, players can occasionally get lucky and beat the casino's statistical advantage at any given time. However, in the long-run, the statistics will always catch up and favour the casino.
Although casino games are games of chance, there are ways in which you can increase your chances of 'beating the statistics', or at least sway them more in your favour. To do so, you must grasp the two main aspects that affect your winnings chances – namely payout ratios (also known as Return to Player) and variance (also known as game volatility).
In this article, we will give you a detailed explanation of how RTP percentages and variance work. We will also look at how you can alter these two factors to make your betting system more profitable in the long-run.
The principles explained in this article can be applied to both slots and table games, or any other game of chance in which a casino collects bets and pays out potential winnings.
How RTP Percentages Work
Return to Player (RTP) is a term that expresses the average percentage of stakes a game returns to players as winnings over time.
It is essential to keep in mind that these numbers are based on an infinite number of rounds. Therefore, they do not represent the return you can expect during any given gaming session.
In other words, playing a game with an RTP of 97% does not mean you will win 97 out of 100 rounds.
What it means is that 97% of all placed stakes will be distributed as winnings to all players. The remaining 3% is the casino's profit, or house edge if you will.

RTP Percentages In Roulette
Roulette has different RTPs, depending on which version of the game you play and what sort of bet you place. For example, the RTP will change dramatically when you bet on a single number instead of placing a side bet, as the odds of these outcomes are very different.
European Roulette has an RTP of 97.3%, while American has a significantly lower RTP of 94.74%. This difference has to do with the additional zero that is found in American Roulette, which effectively increases the house edge significantly and alters the odds of each outcome. In other words, you have a much better chance of winning on European Roulette.
To calculate the RTP of European Roulette, you must look at the probability of winning. There are 37 numbers in total on the wheel. Leaving out the zero, this means there are 18 numbers of each colour, and winning a bet on colour pays two times the bet.
Therefore, to calculate the game's RTP when you bet on numbers, you apply this formula:
18 (numbers of each colour) * 2 (pay-out) = 36 / 37 (total amount of numbers on the wheel) = 97.3%.

RTP Percentages In Blackjack
As Blackjack rules may vary from one casino to another, RTP percentages differ as well. However, generally, a player using a basic Blackjack strategy can expect an average return of 99.5%.
When it comes to Blackjack, the RTP changes as the game progresses due to the fact cards are continuously leaving the deck. Depending on which cards are left in the shoe, the RTP may range from 95% to 102%.
Card counters try to benefit from this fact by counting cards and estimating the RTP. They will then look to place high bets when they believe the RTP has risen above 100%.

Slot Machine RTP
Online slot machines generally have RTPs between 93% and 97%. Slot machines in land-based casinos typically have much lower RTPs than online slots.
A slot machine's RTPs is determined by the game symbols, the payout table and the specific rules that apply to the game. Usually, the game manufacturer will set a fixed RTP for the game, however, some slots have an adjustable RTP that allows the casino to request what the RTP should be.
If you want to know which online slots yield the biggest potential returns, we suggest you start by exploring these volatile slots:
-
Wolf Gold
96.01%
Pragmatic Play -
Primal Hunt
96.10%
Pragmatic Play
-
Gems Bonanza
96.51%
Pragmatic Play -
Wild Walker
96.55%
Pragmatic Play -
Curse of the Werewolf Megaways
96.50%
Pragmatic Play
Slots Volatility Explained
Casino games have something called variance, or volatility, which determines how often you win and the general size of your winnings.
In slots, volatility is expressed as a number on a scale, or classified as High, Medium or Low. In table games, variance is relative to the kinds of bets you place.
As wins are always a multiplication of your stake, you can also look at volatility as the size of your bet multiplier.
No matter how you choose to look at it, this is what you need to know about game variance:
- Low-volatile games – You may win rather frequently but mostly get smaller wins.
- Highly volatile games – Wins are often far and few in between. However, when you do win, you often win big.
The rule of thumb is that high-variance games are better than low-volatile ones.
Here are three aspects that support this claim:
- Since volatile games yield much bigger potential returns, it is easier to achieve a satisfactory win in one game round.
- You will play fewer rounds, which positively affects the RTP of your betting system (we explain this in more detail in the subsequent section).
- The multipliers in high variance games allow you to achieve the same win amount with a smaller stake. In the long-run, this reduces the total sum of your bets, and therefore, also your losses.
When talking about high-variance games, it is essential to make a distinction between table games and slots.
Slots have fixed variance, meaning you alter the variance by choosing the appropriate game. In table games, variance is relative to the kinds of bets you place, or the hand you are dealt.
Here are a few examples of slots with different volatility:
High volatility:
-
Curse of the Werewolf Megaways
Pragmatic Play -
Primal Hunt
Pragmatic Play
Medium volatility:
-
Monster Pop
Pragmatic Play -
Jungle Gorilla
Pragmatic Play -
Money Mouse
Pragmatic Play
Low volatility:
-
Three Star Fortune
Pragmatic Play
Understanding The RTP of a Betting System
If you want to play smart, you must distinguish between the RTP of a particular game and the RTP of your chosen betting system.
A betting system is defined by how you manage stake and variance during a playing session to reach a specific goal. It also factors in which games you play and the decisions you make about when to stop playing.
To calculate the average return of a betting system, you compare the ratio of overall winnings of players who achieve their goal to the net losses of those who do not.
Many players use winnings from a previous round in their next bet, and although this might seem like a 'safe' strategy, statistics show the opposite.
The optimal betting system is one which has an RTP almost identical to the specific game you are playing. To achieve such an RTP, you cannot merely bet your previous winnings.
Theoretically, the best option is to bet your entire budget in one round and then keep betting all-in until you either lose your entire bankroll or reach your goal.
Here is an example of how to implement a betting system:
Assume you have $100 to spend on European Roulette and that you have decided to stop playing when you have a bankroll of $900. In this instance, your best option is to bet your entire budget on a four-number combination which has an 8 to 1 return. You might lose your entire budget; however, there is a 10.8% chance you achieve your goal – and those are rather good odds!
How Variance Affects a Betting System
To demonstrate how a game's variance can alter a betting system's RTP, we have conducted a series of tests.
In our experiment, we simulated a scenario where two players played European Roulette. The experiment assumes both players have a $100 budget and that they will stop playing when they have a bankroll of $500 or more.
To clarify, in this experiment, 'a win' is defined by a player achieving a total bankroll of at least $500.
The players proceed to place bets with different variance:
- Player A bets $10 budget on a number. This is a high variance bet with a return of 36 to 1.
- Player B places bets on colours which has a low variance of 2 to 1.
To simulate what would happen, we ran a vast number of simulations which yielded the following results:
- Won 14.8% of all attempts
- Played an average of 16 rounds
- Had an average win of $648
Subtracting the initial stake, this gives the player a net win of $548.
To calculate the RTP of Player A's betting system, we must calculate the ratio of net wins to net losses:
- Net wins of $548 x 14.8% = 8,110.4
- Net losses of $100 x 85.2% = 8,520
8,110.4 (net wins) / 8,520 (net losses) = 95.19%.
Player A's betting system proved to have an RTP of 95.19%.
The same test revealed that Player B only won 5.15% of the attempts. The player also reached an average bankroll of $500 and achieved a betting system RTP of 21.42%. However, Player B did play an average of 247 rounds, meaning the player got to spend a lot more time playing.
How Bet Size Affects The RTP of a Betting System
In casino games, win amounts are always a multiplication of your stake. Therefore, your betting system's RTP is also affected by the bet size you are playing with. The larger your bets, the higher the RTP of your betting system – at least generally speaking.
To show you what impact bet size may have on your betting system's RTP, we have conducted another test, similar to the one we have previously discussed.
Two players play European Roulette with a $100 budget, intending to stop playing when they have reached a bankroll of $500 or go bust.
The two players use slightly different strategies:
- Player A bets $20 per game round.
- Player B bets $5 per game round.
- Both players bet on colour.
After having simulated one million instances of Player A's strategy, we found that this player reached the $500 target in 10.9% of all attempts. The player played an average of 84 rounds and achieved a betting system RTP of 48.68%.
Player B, however, only reached the $500 goal in 0.88% of one million game rounds. The player played an average of 706 rounds and ended up with a meagre betting system RTP of 3.55%.
The lesson learned from this experiment is clear – you do get to play a lot longer when betting smaller amounts on low variance bets; however, your odds of winning substantial amounts are significantly reduced.
On the opposite side of the spectrum, we have high variance bets with large stakes. To demonstrate the impact of such a strategy, we ran a similar test in which we assumed a third player placed the entire $100 budget on a one-number bet.
After having simulated one million rounds, we found that the player would win 2.7% of the time. However, when successful, this strategy yielded a massive $3,600 win which resulted in a betting system RTP of 97.4%.
How To Find The Best Betting Strategy
As we can conclude from the given examples, a profitable betting system needs to consider the odds of achieving a particular win and the win's size. It also needs to take into consideration how much time you intend to spend playing.
In the table below, you can see the results of different simulations we have made. These simulations assume you have a $100 budget, and that your goal is to stop playing when you have a bankroll of $500 or more.
Looking at the table, you will see the RTP of a particular betting system change as bet size and variance are altered. When it comes to Roulette, you adjust variance by changing the kinds of bets you place. If you play slots, variance will vary depending on which game you choose.
Bet Size | $0.5 | $1 | $2 | $5 |
---|---|---|---|---|
Number | 9,55% x $505 | 13,9% x $511 | 16,15% x $522 | 16,7% x $555 |
RTP 42,76% | RTP 66,35% | RTP 81,27% | RTP 91,21% | |
3832 rounds | 1083 rounds | 292 rounds | 52 rounds | |
Color | 0% | 0% | 0,0015% x $500 | 0,88% x $500 |
RTP 0% | RTP 0% | RTP 0,006% | RTP 3,55% | |
7399 rounds | 3698 rounds | 1850 rounds | 706 rounds | |
Number | 14,8% x $648 | 12,8% x $760 | 5,33% x $1 825 | 2,71% x $3 600 |
RTP 95,19% | RTP 96,88% | RTP 97,12% | RTP 97,40% | |
15,9 rounds | 4,73 rounds | 1,97 rounds | 1 round | |
Color | 5,13% x $500 | 10,85% x $500 | 15,94% x $500 | 17.9% x $500 |
RTP 21,62% | RTP 48,68% | RTP 75,85% | RTP 87,21% | |
274 rounds | 84 rounds | 15 rounds | 3 rounds |
As you can see in the table above, high variance bets on numbers have a much higher betting system RTP than low variance bets on colour. In a slot game, this means your betting system RTP would increase if you played highly volatile slots.
If your goal is to spend a bit of time playing and have good odds of winning, we recommend you choose a high variance game and place relatively small bets.
In A Nutshell
- Game RTP percentages are based on a vast number of rounds. They reflect the percentage of stakes a game returns to players in the form of winnings over time.
- The RTP of your betting system is relative to the RTP of the actual game, the game's variance and your chosen bet size. You must also factor in your overall goals and the time you intend to spend playing.
- The potential size of winnings determines a game's variance.
- High-variance games are usually your best option. You are more likely to win and reach your goal in a high-variance game than in a low-variance game with a high RTP.
- The higher the variance, the more likely you are to turn smaller stakes into massive wins.
- Assuming you play with a fixed bankroll, the RTP of your betting system increases when you place bigger bets.
- If you want to play for fun and still get a chance to bring home substantial wins, you should play high-variance games with smaller stakes.
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