Online slots have come on awful lot in recent years and they’re now almost unrecognisable compared to the classic slot machines that they were originally based upon. These days, slots feature graphics to rival the best video games in the world, while even the gameplay on offer has developed a lot, again drawing influence from other types of video games.
But while the exterior of games may seem very different, under the surface they tend to operate very similarly, particularly when it comes to slot odds, payouts and return to player (RTP) rates. In the following sections, we’ll explore in more details the mechanics of online slots and look at what the chances are of winning while playing these games.

Slots Are Games of Chance – About RNG

Despite what you might have heard, slots are games of complete chance and every single spin has the same chance as any other of being a winner. There are no set structures or patterns when it comes to determining when a slot game will pay out as every spin is completely independent and the result is produced using RNGs.
Indeed, the way slots generate results is very similar to that of rolling a dice (although with different odds). On any single roll of a dice, the chance of hitting any number in particular is 1 in 6, regardless of what any of the previous rolls of the dice have been. Slots are essentially the same, but with many more variants.
Slot games feature many symbols, with millions of potential outcomes and combinations of symbols. However, not all online slots have the same odds or pay outs, as this is dependent on how the game has been structured. Slot odds are calculated by the Hit Frequency, which shows the probability of any combination happening.
So while on a dice, any number has a 1 in 6 chance of appearing, the symbols on a slot machine can have varying chances of appearing, which can therefore affect the odds of it happening – and thereby determining how much you can potentially win.

To demonstrate this point, we’ve come up with our own fantasy slot. Let’s call it “Lucky Aquarium”. To make things simple, it has five different symbols: treasure chests, golden fish, purple fish, yellow fish and red fish. The pay out table make look something like this:

Combination	Payout	Hit Frequency
Five treasure chests	2500	0.001%
Five golden fishes	1000	0.015%
Five purple fishes	400	0.05%
Five yellow fishes	50	0.5%
Five red fishes	5	7%
Total	3955	7.566%

As you can see, finding five treasure chests would pay out significantly more than finding five fish, even though they both require the same number of symbols aligning. This is because there are effectively less treasure chests to be found, making it a less likely outcome (hence the low hit frequency) but also why you’d be rewarded with a much bigger pay out.

Players should note, though, that all slots have different values in terms of both hit frequency and pay outs – so just because you know the numbers for one game, doesn’t mean you know it for others. As a general rule of thumb, though, you’ll find each spin on a slot will have about a 40% chance of hitting a winning line, although the value of this payline can vary massively.

Return-to-Player (RTP) and House Edge

While slots players often hope to scoop a big prize while playing, casinos will of course always need a house edge in order for them to continue operating.
The outcome of any single spin is always random and neither the casino nor software provider can decide if someone wins or loses. However, due to the game’s odds, casinos can ensure a profit in the long-term. This house edge can be established by calculating the return to player rate. A typical return to player rate of 95%, for example, will ensure the casino a profit of 5% on the game in the long term.
Of course, as we’ll see in the next section, that doesn’t mean that the player will always lose by 5% – that’s just the average. So sometimes the player may lose more and sometimes they’ll win significantly more. It all comes down to luck.
RTP determines the long-term outcomes of all slot games, as it is based on the probability for each and every outcome as well as the value of each of those outcomes.

How Much Do Slots Pay Back?

All online slot games at Mr Green will show their return to player (RTP) rate in the game description. This could be any number up to 100%, but it is typically in the mid-90s. Essentially, the RTP rate shows the house edge – or how much the casino expects to make in the long-term on any given game.
So, if a game has a 95% RTP rate, €95 of every €100 spend on the game would return to players via winnings, while the remaining €5 would be profit for the casino. Of course, if you spend €100 on a slot, you’re not guaranteed to get €95 back – sometimes you might win more, and sometimes you might get less back. It all comes down to chance.

Indeed, to give you a better idea of how RTP is calculated, let’s take another look at our “Lucky Aquarium” game to see how the numbers fit together.

Combination	Payout	Hit Frequency	Return to player (RTP)
Five treasure chests	2500	0.001%	2,5%
Five golden fishes	1000	0.015%	15%
Five purple fishes	400	0.05%	20%
Five yellow fishes	50	0.5%	25%
Five red fishes	5	7%	35%
Total	3955	7.566%	97,5%

As you can see, the total chances of winning with any combination on our simplified game can be used to calculate the total RTP. Of course, our games typically have a lot more different ways to win, so this figure would typically be a lot more complicated, but it should give you an idea of how the numbers work.

Why Play Slots? What Are the Chances of Winning?

There are lots of reasons why people play slots online, but the main reason is that it can be a lot of fun. Playing slots is very easy and doesn’t take up too much brain power. However, you can still get a real thrill while playing as it is very much a game of chance. There are very few decisions to be made, so there shouldn’t be any stress either.
Naturally, as well as having fun, people also play online slots in the hope that they can win a prize. Payouts can come in many shapes and sizes when playing slot games – often varying from game to game.
Some of the most popular games to play at Mr Green are progressive jackpot slots. While “normal” jackpot slots have a fixed top prize (and are also hugely popular), progressive jackpot games see the total jackpot amount continue to rise the more people play the game without the jackpot being hit. This can lead to some seriously big prizes coming up for grabs and lead to more and more players playing – which in turn makes the jackpot amount surge even higher until someone scoops the lot.
While there’s no way to increase your chances of winning on any single spin when playing slots online, you can boost your value by taking advantage of the many promotions and offers available from Mr Green.

Slots – Odds, RTP and Payouts