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Online Slot RTPs Explained

Posted by THEPOGG on Mar 23, 2021

This article was written by ThePOGG.

Slots games offer something entirely unique as far as gambling games are concerned. In gambling terms, they are a modern invention. The other games that we associate with gambling are far older and have evolved round more classical ‘instruments of randomness’. What do I mean by that? They all have a physical device that is used to generate the random outcome that the player bets upon. Roulette has the spinning wheel. Players can see how many slots are on the wheel and as such intuitively understand the likelihood of a particular outcome. Craps and Sic Bo are played with six-sided dice. Again players can understand both how randomness is created and what the chances of different outcomes are. Bingo, lotteries and Keno all use a system of balls that the results are drawn from. Players can intuit from the number of balls being played with a rough concept of the odds of the game. Baccarat, Blackjack and the various table poker games all use decks of cards. Even Video Poker – which is a far more recent invention – still use a digitally simulated deck of cards.

In all of the above cases there is a physical device that the player can visually see and understand which creates randomness. While in the long History of Slots early slot type games did start out either with a physical device or mimicking a physical device – very early slot machines were based on a pack of cards and even once reels were developed for a long time these were physical reels that were constrained in the number of symbols they could contain by the physical space available – slot games have long since evolved past the constraints of physical devices.

The evolution of video slots means that the ‘reels’ displayed to players could be of any length that the game developer desires. There are no physical limitations. Consequently, there is also no way for the player to reasonably understand or intuit what the odds they are facing are. That is where RTPs come in.

What is the Return To Player (RTP)

Return to Player (RTP) figures are a way of helping players understand how expensive a particular game is to play.

RTP is expressed as a percentage. This percentage tells you how much of every 100 credits wagered will be returned to players as winnings. So, if a game has an RTP figure of 96%, that means that on average for every 100 credits wagered on the game, 96 credits will be returned to the players in winnings over the long term.

It is important to note that RTP figures are an average. They do not tell you what will happen in the short term. If you could say with certainty, because of the RTP figure, that every time you wagered 100 credits that you would get back 96 credits (using the example of a 96% RTP given above), there would be no fun or excitement in gambling. The entertainment offered by gambling is intrinsically tied to the unknown outcome, to the risk and potential reward. So, when we say ‘this game has an RTP of 96%’ what we mean is that across all players, and over millions of rounds of play, this game will return, on average, 96 credits for every 100 credits wagered. Some players will win big. Others will lose far more than the projected 4 credits per 100. And therein lies the attraction of gambling.

To date the UKGC is the sole regulatory authority to make it a requirement for all gambling operators to make available all game RTP figures to players.

Why RTPs are not the best way to explain the cost of a game to players

RTP figures are not the best way to explain the cost of a game to players. Why do I say this? Consider how every other product that you can purchase is priced. When you go into a supermarket, do you expect to see the prices expressed as the change you will get back from 100? Of course not. That would be a silly way of telling you the price as you would then have to work out in your head what the actual cost of the item you want to buy was. Shops simply tell you the cost of what you are buying, which is naturally easier to understand.

The more logical and player-friendly approach would be to tell players the cost of their play directly. This figure is called the ‘House Edge’. House Edge can be worked out in a simple fashion, all you need to do is subtract the RTP from 100. So if you have an RTP of 96.1% – like the popular slot game Starburst – the House Edge is 100 – 96.1 = 3.9%.

For reasons known best to those in charge, the gambling industry has opted to inform players of the cost of play by telling them the percentage of wagers that get returned to the player. This is counterintuitive and it seems likely this method was selected for marketing reasons. It sounds far better to players to say “we give back 93% of everything you wager” than it does to say “we keep 7% of everything you wager”. It is also harder to quickly compare the cost of games using RTP. Consider two games with a 98% and 95% RTP. The difference does not seem that significant. These numbers seem so close together. But when expressed as House Edge – 2% and 5% – it can quickly be seen that the second game is more than twice as expensive as the first.

The ship has already sailed on this particular issue. The industry has already accepted RTP figures and educated large numbers of players so they look for and expect this figure. But House Edge is the better figure for players.

How are RTPs calculated

There are two methods of calculating RTP, a simple mathematical method and a more complex method that involves simulation of the game.

The Simple Method

For more basic games, it is straightforward to calculate the RTP using some basic maths. Let’s use European Roulette (European Roulette has only a single ‘0’ slot compared to American Roulette which has ‘0’ and ‘00’). Taking one of the easier bets to understand, let us say that the player bets 5 credits on ‘Red’ which is an even money bet (meaning, if you win you will get your bet back and the same amount in winnings). On a European Roulette wheel, there are 18 Red slots, 18 Black slots, and 1 ‘0’ slot (which is green). So there is an 18 out of 37 chance of you winning 5 credits and a 19 out of 37 chance (the 18 Black spots and the 0) of you losing 5 credits. So the expectation for this bet would be as follows:

(5 x 18/37) + ((-5) x 19/37) = -0.14

The negative means that we expect to lose this amount.

To calculate the RTP of the game, we divide the loss by the total amount bet and multiply by 100 (which gives us the House Edge) and subtract the answer from 100:

0.14/5 x 100 = 2.70% (the House Edge)

and subtract this from 100:

100 – 2.70 = 97.3%

The RTP of the Red bet on European Roulette is 97.3%.

To give a more complicated example, let’s look at betting straight-up on a number on Roulette. A straight-up bet (betting on a specific number) pays 35 to 1, meaning that if you win your bet will be returned and you will receive winnings of 35 times your bet in winnings. In this instance, you have a 1 in 37 chance of winning and a 36 in 37 chance of losing. So the expectation for a 5 credit bet would be:

((5×35) x 1/37) + ((-5) x 36/37) [(wager x winnings) x (probability of win)) + (loss x (probability of loss))] = -0.14

The negative means that we expect to lose this amount.

To calculate the RTP of the game, we divide the loss by the total amount bet and multiply by 100 (which gives us the House Edge) and subtract the answer from 100:

0.14/5 x 100 = 2.70% (the House Edge)

and subtract this from 100:

100 – 2.70 = 97.3%

The RTP of the straight-up bet on European Roulette is 97.3%. (almost all bets on Roulette have the same House Edge/RTP)

The Complex Method

The method described above is fantastic for managing basic games. It can technically be applied to any game. As long as you know the probabilities of the outcomes the maths exist to build a formula and work through to the answer. However, the more complex the game the more complex the mathematics required to determine what the RTP is becomes. Even small errors can have a significant impact on the answer received. Slots games – with huge numbers of possible combinations fall into the ‘very complex’ category. An alternative method that is less prone to human error is required in these situations.

And this is where Testing Labs come in. A Testing Lab takes a game and plays millions of rounds. The record the total amount bet and the total amount won. By dividing the total won by the total bet and multiplying the answer by 100 the RTP can be determined.

Why do you need so many rounds of play to calculate the RTP this way?

Probability tells us the frequency with which events are likely to occur. But it an average over the long term. If you flip a coin twice are you guaranteed to get 1 head and 1 tail? Obviously not. That’s the most likely result, but it is perfectly possible to get 2 heads or 2 tails. As the number of trials increases, the chance of us being around 50% heads and 50% tails improves.

Slots games are what is known as ‘high variance’. This means that there are some very big winning combinations that are very rare. To balance out these huge wins, there is a high frequency of small losses. Sometimes these rare wins can have probabilities of 1 in hundreds of thousands or millions. When a win has a probability of 1 in 1,000,000 it is entirely possible to play a million spins without ever receiving this winning combination. It is also possible that over the course of a million spins you will receiving this winning combination more than once.

Here are two examples from real life:

i) The Italian Lottery: In 2005, the Venice lottery results had failed to draw the number 53 for 152 consecutive draws. This lottery is played with 90 balls and 5 are drawn. That means that over the course of 152 draws, 760 balls were drawn and 53 did not turn up. At the start of any draw, the odds of 53 being picked are 1 in 90.

[For those interested in the probability of not drawing 53 over 152 draws, this can be calculated as shown below:

((89/90) x (88/89) x (87/88) x (86/87) x (85/86))^152 = 0.000169 or approximately 1 in 5932]

This occurrence – which isn’t even all that rare in probabilistic terms – reportedly resulted in a significant number of Italian players wagering far more than they should have, mistakenly believing that because the number 53 had not come out for such a long period, it was more likely to be drawn soon (this is called the Gambler’s Fallacy – the lack of 53’s in previous draws did not in fact make 53 any more likely to be drawn in future draws). Tragically this appears to have resulted in 4 deaths and 53 people losing their homes to repossession.

ii) Video Poker – In my past I have played a LOT of Video Poker. When playing one particular game, receiving a Royal Flush (the best hand) had a probability of approximately 1 in 20,000. In one very memorable playing session, I drew two Royal Flushes within 18 hands. Conversely, playing the same game, I experienced a period of over 100,000 hands without any Royal Flushes.

The point in the two above examples is that while probability tells us what should happen, it does not tell us what will happen. Rare events are not uniformly distributed. In the short term, these very rare big winning events that are standard in slots games can occur more or less frequently than expected. This is variance in action. It is only over the long term that the average, that is predicted by the probability, will be reached.

For that reason, to accurately derive the RTP of a game, the rarer the big winning combinations the more rounds it will take to get an accurate average result. If a game has a big win that has a probability of 1 in 1,000,000, it may take hundreds of millions of spins to ensure that this rare win has been triggered at its natural proportion. This is especially important as with these big rare wins so much of the RTP for players is tied up in these being triggered. If a data set includes too many of them (like me hitting two Royal Flushes in 18 hands) it will end up making the game look far more generous to players than it is. If the data set includes too few of these rare wins, the game can end up appearing far more expensive than it really is. Big data sets are required to ensure we have an accurate representation of how expensive a game is to play.

The difference between real RTP and theoretical RTP

To complicate matters a little, there are actually two different types of RTP figures commonly shown by gambling operators. The figure we are discussing here is the ‘theoretical RTP’ (tRTP – or just RTP in any other section of this article). The tRTP is the figure that tells you how much on average the game will cost players, the return that the game will move towards over the long run. This figure is useful to players and gives them real information about what they can expect in the future.

The other RTP figure that is commonly shown on operator sites is the ‘real RTP’ (rRTP). This figure is the return that the game has given to players over the immediately preceding short period, usually several thousand spins but nowhere even close to enough for the figure to accurately reflect the actual expectation of the game (which is the tRTP). This figure is used to encourage players to believe in the Gambler’s Fallacy – that the short-term results give some indication of what is going to happen in the future. They are used to categorise games as ‘hot’ (i.e. players have been winning on this game recently) or ‘cold’ (i.e. the game has not paid out what it is expected to and as such may be ‘due’ to payout). This is totally incorrect. rRTP figures tell players absolutely nothing useful and can encourage players to believe in dangerous superstitions. Where you see a rRTP figure, or games being branded as hot/cold, ignore this entirely – it does not tell you anything that can help you.

Where can I find a game’s RTP?

The next question is where can you find a game’s RTP information? With UKGC licensed operators required to provide this information, most of the biggest names in the industry are already ensuring that RTP information is available for players. But how this is made available varies. Some operators will have a centralized page housing the RTP figures for all their games in one place. Others will have individual game information pages with this information. Still others will use various graphical interfaces (mouse over effects etc) to show RTP information. As there is no standard practice there is no hard and fast rule we can provide for where to locate RTP information at all operator.

However, the majority of software providers are now building the game RTP information somewhere inside their game information. Given the standard structures that most software providers use to construct their games, RTP information tends to be consistently locatable in the same place for all games made by a single manufacture. We will show you some of the major ones below:


NetEnt keep their RTP information in their game help file. This is usually found by clicking the ‘?’ icon at the bottom left of the game screen. You will find the RTP information towards the bottom of this page as seen in the screenshot of Starburst below:


Surprisingly, given that Playtech can be considered an industry giant, this software provider has not yet taken steps to build in RTP information that players can access within their games. Instead they appear to be relying on individual operators to provide this information to players outside of the games.


As with Playtech, Microgaming – another titan of the industry – are significantly behind the times and do not appear to provide RTP information for their games as standard in their game documentation. Players will have to look for this on individual operator websites.


IGT provide RTP information in the paytables of their games. This can be found towards the bottom of the page in a section called Payback Information as can be seen in the below screenshot of Cleopatra:

Big Time Gaming (BTG)

The RTP information for BTG games is a little tricky to find. Click the three horizontal lines at the bottom left of the screen to open the paytable. Then click the ‘Help’ tag at the top. Scroll through the pages and you will generally find the RTP information towards the end of the lists as shown in the screenshot of Bonanza below:

Elk Studio

Elk Studio games have a three horizontal line symbol at the top left of the screen. Click this then then ‘i’ symbol and you will find the RTP in the middle of the game rule just before the information on ‘Betting Strategies’ where the software encourage players to engage with various progression betting strategies (which is a highly questionable practice). This can be seen below in the screen shot of the Taco Brothers game:

Play N Go

With Play N Go games, click the three horizontal lines at the bottom right of the screen, then click click ‘Game Rules’. The RTP information can be found within the text towards the bottom of the screen as can be seen below for Rich Wilde and the Book of the Dead:

Pragmatic Play

Pragmatic Play games make the RTP fairly easy to find. Click the ‘i’ button at the bottom left of the game window, scroll through the paytable until you find the game rules and you will find this information at the bottom of that screen, as shown below on The Hands of Midas:


With Thunderkick games there is a grid of 9 dots (3×3) on the left-hand side of the screen. Click that, then click the icon that looks like a piece of paper with writing on it. That will take you to the game rules and you will find the RTP figure towards the top of the document as can be seen below for Esqueleto Explosivo:


On WMS games you will find the RTP information included with the paytable. Click the ‘?’ button at the bottom left of the screen, a new window will open. Scroll to the bottom and you will find the RTP information at the very bottom as shown below for the Wizard of Oz: Ruby Slippers game:

Yggdrasil Gaming

For Yggdrasil games, click the ‘+’ sign at the bottom left of the screen, then click ‘i’, scroll to the bottom of the window and you will find the RTP information under the heading Return To Player as shown below on Vikings Go To Hell:

What are the best RTP games?

So the broad message in this article is that you should always look at the RTP figures for the games you are thinking about playing and use this as a guide as to whether you are getting the most entertainment bang for your buck. You do not want to end up playing a game that is charging you significantly more than average. Not only are you less likely to win, but your bankroll is likely to diminish at a quicker rate.

To help you select a slot game with a good RTP, we have compiled some of the best RTP slot games for some of the bigger providers below. For comparison purposes, we have also included one of the provider’s popular games at the bottom for some providers. We have also excluded games that we think likely require a skill-based strategy, as not every player is going to be able to achieve the listed RTP and often the optimum strategy is not in the public domain:


Blood Suckers 98%

Fishy Fortune 97.9-95.4% (Progressive Jackpot game – the top RTP will only be reached with a far above average jackpot pool)

Kings of Chicago 97.8%

Devil’s Delight 97.6%

Simsalabim 97.5%

Starburst 96.1%


Hot Ink 97.5%

Retro Reels – Extreme Heat 97.5%

Couch Potato 97.43%

High 5 97.43%

Jungle 7’s 97.43%

Immortal Romance 96.86%


Golden Tour 97.71%

Jungle Boogie 97.4%

White King 2 97.3%

8 Treasures 1 Queen 97.29%

Desert Treasure 97.1%

Batman Begins 95.03%


IGT games offer the operator the option to choose RTP settings, so while the below may potentially be the best games, you need to check with the operator what the RTP of any given game is:

Ghostbusters Plus 93.99-98%

Gong Xi Fa Cai 92.01-98.07%

Wheel of Fortune Triple Action Frenzy 97%

Wheel of Fortune Hollywood 96.99%

Monopoly Money 94.03-96.78%

Cleopatra 95.02%

Big Time Gaming (BTG)

White Rabbit 97.29-97.44%

Starquest 96.90%

Queen of Riches 96.90%

Opal Fruit 96.75%

The Final Countdown 96.56-96.65%

Bonanza 96%

Elk Studios

Ho Ho Tower 96.4%

Poltava 96.4%

Taco Brothers Saving Christmas 96.4%

Wild Toro 96.4%

Taco Brothers 96.3%


All games have a standard RTP of 96%.


The Ruby 97.5%

3 Charm Crush 97.23%

Hot Shots 97.15%

Shaolin Spins 97.15%

Fruit Boxes 97.1%

Leander Games

Apollo God of the Sun 97.17%

Patrick’s Jackpot 97.17%

Scrooge’s Jackpot 97.17%

Trick or Treat 97.17%

Megadeth 96.97%


Simply Wild 98%

Columbus 97.03%

Bugs N Bees 96.99%

Bloody Love 96.68%

Spectrum 96.61%

Book of Ra Deluxe 95.10%

Play N Go

Cash Garden 98%

Ring the Bell 97.03%

Ring the Bell Deluxe 97.03%

Spin Win 97.02%

Ace of Spades 96.96%

Rich Wilde and the Book of the Dead 96.20%

Pragmatic Play

Gold Train 97.16%

Caishens Gold 97.08%

Medusa Strikes 97.08%

888 Dragon Happy Luke 96.84%

Eye of the Storm 96.71%


Big Bad Wolf Christmas Special 97.34%

Big Bad Wolf 97.30%

Beowulf 97.21%

Sinbad 97.10%

Treasure Island 97.10%

Red Tiger

Zeus Lightning Power Reels 98%

Wild Spartans 96.43%

Chinese Treasure 96.31%

Jackpot Quest 96.30%

Dragons Luck 96.29%


1429 Uncharted Seas 98.63%

Magicious 97.57%

Bork the Berserker 97.30%

Bork the Berserker Hack and Slash 97.30%

Toki Time 97.10%


WMS have a large selection of games with ‘bonus buy’ features. They require very large bets to obtain the best RTPs. As such we have excluded these games from the below list.

Pride and Pray 97.52%

Crime Pays 97.04%

Napoleon and Josephine 97.03%

Casino Island 96.90%

Casino Island 2 96.90%

Yggdrasil Gaming

1 Left Alive 97.0%

9k Yeti 97.0%

Baron Samedi 97.0%

Nitro Circus 97.0%

Wilhelm Tell 97.0%

Volatility – the other game selection factor

Another important piece of information is what game providers call the “volatility” of the game. This is not directly part of the RTP – and as such is only tangentially connected to the topic of this article – but it nevertheless makes a useful tool for players to use alongside the RTP figure when assessing which games they want to play.

The volatility – or variance to use its more common mathematical terminology – is a measure of how big the likely fluctuations in your balance are likely to be. A low volatility game is likely to pay out small wins frequently. A high volatility game would be expected to pay out big wins rarely and these would be balanced out by long losing streaks.

This should make sense to most people – if a game is going to pay out millions to a single player, it is going to have to balance this out by lots of other players losing. Lotteries are a perfect example of a high volatility game – lots of losers and a small numbers of big winners.

For this reason volatility *can* be useful in helping players pick a game that suits the type of gambling experience that they are looking for. If you don’t mind losing a lot, but want to play with the chance of having a life-changing win, you want to play a high volatility slots game. Conversely, if losing too quickly is likely to upset you or leave you feeling dissatisfied with your gaming a low volatility game may be a better choice.

There are two caveats to this however. Firstly, broadly speaking, when considering all casino games with few exceptions slots games are all considered ‘high variance’. Compared to most other casino games, the majority of slots – even those labeled as ‘low volatility’ would be considered high variance. So while you can choose a low volatility slot the chances of having sustained losing streaks are still far higher than the likes of Blackjack, Baccarat or even Roulette.

Secondly, while some software providers have started giving volatility ratings, this is far from universal. More importantly, there is no standard accepted across the industry in what can or should be considered a low, mid or high volatility game. This means that what one software provider considers a ‘low volatility’ game, may be considered mid, or high for another software provider. In short, these gradings are only applicable when comparing games from the same software provider.

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The above information is what we believe to be the the legal status of online gambling, however information on this topic is limited and hard to find. We accept no liability for any errors or ommissions. It is the reader’s responsibility to ensure that they know the legality of online gambling in their country before engaging with any online gambling service.