Slot machines are one of the most popular pastimes in both online and land-based casinos. Many players from all over Spain (and not only) go online every day to try their luck with their favourite online slots or to search for new and more fun and exciting slots.
All slots obviously have different features. Their graphics, settings and animations, for example, immediately catch the eye. The player becomes aware of the symbols, jackpots and other rules of the different slot machines only in a second.
The Rtp Of Online Slot Machines: The Mathematical Principle
The RTP percentage of a slot machine is one of the most important characteristics to consider before deciding to gamble. The acronym “Return To Player” tells you how profitable a slot machine is. In general, RTP is the rate of return of a game.
To better understand what RTP means, we can turn to the world of probability and mathematics. Imagine that during a gaming session you bet 100 coins. If the RTP of the slot machine is 95%, the statistic says that you will most likely have 95 coins left when the game ends.
Keep in mind that the RTP is a theoretical figure and that the outcome of each game may be different. The RTP only indicates what the players’ average balance is, but (as per the example above) there are those who lose more than 95 coins, and there are also those who win more than 100 coins.
In addition, the best online slots generally have an RTP that exceeds 90%. We can say that even a 94% return to player percentage is not very convenient in an online slot machine. Things get really interesting if the payback percentage goes up to 97, 98 or even 99%.
We have to underline that this is an absolutely mathematical calculation and therefore, in the long run, the theoretical payback percentage for the player will necessarily be equal to the real one.
Finally, this calculation includes net winnings, as winnings on online slot machines are taxed at source and therefore under the full responsibility of the operator.
The RTP percentage is absolutely reliable. When a software house, such as Novomatic or NetEnt, develops a new slot machine, they have in mind from the beginning what the RTP of the slot machine is going to be. Furthermore, if you play in regulated jurisdictions, with the DGOJ online casinos, you can be sure that the RTP of the games, and also the performance of the RNG, will have been verified by at least one independent statistical laboratory (GLI, BMM TestLabs, Trisigma Q3) of the developer that manufactured it and the casino that offers it.
Volatility In Online Slots

Attention: we talked earlier about data in the form of numbers. There are many other factors to consider when choosing a slot machine. For example, the presence or absence of jackpots and the volatility of the game.
What does this mean? There are slot machines that pay out often but without giving excessive prizes; on the contrary, there are slot machines that rarely pay out but give higher value prizes. In short, do you like a slot with more variance or a little more volatility?
Volatility is fundamental to understanding the type of dynamics of a slot machine and determines the interaction between two factors, i.e. the number of times you bet and the number of times you win a prize.
The higher the volatility, the sharper the relationship between these two elements, increasing the prize amounts and also the number of spins required for the rewards to arrive.
The Eight Online Slot Machines That Pay The Most
For those who wish to plan a slots strategy from the outset, here is a list of the 8 online slot machines that have the highest RTPs, all available from the wide selection of slot machines offered by Slots Web.
#1 Blood Suckers – 98%

Blood Suckers is a NetEnt developed slot machine starring romantic vampires. The slot is great fun, has simple rules and has a few extra features: classic free spins and a ‘pick em’ bonus that invites the player to open coffins and kill vampires. Too ghoulish? Let’s move on. But if you want more information, don’t miss the Blood Suckers cheats in our review, which reveals all the secrets to winning and having fun.
#2 Rage to Riches – 97.12%
Rage to Riches is a fun slot developed by Play’n Go, surely one of the best slots offered by online casinos and gaming sites, inspired by the world of graffiti, typical of street art. This slot is “generous” and pays well. To learn more about it, just read our review and click here.
#3 A Night Out – 97.06%.
Playtech’s A Night Out slot takes the player among beautiful girls and colourful drinks. The atmosphere is precisely that of an evening in good company spread over 5 reels and 20 paylines. A Night Out also has a great return in monetary terms: well, here we are above 97%.
#4 Desert Treasure – 97.05%
We continue with an RTP above 97% with one of the many online slots inspired by ancient Egypt. Also in Desert Treasure there are 5 reels and 20 paylines. The RPT percentage is slightly lower than the above, but it’s almost impossible to notice.
#5 Steam Tower – 97%
We continue to mention three slots developed by NetEnt. We start with Steam Tower, a modern steampunk-themed slot that offers free spins and multipliers and a very high payout. Its graphics are special and should be tried.
#6 Dazzle Me – 96.9%
Dazzle Me is another very popular Netent slot machine. It comes equipped with 5 reels and 76 paylines, includes stacked symbols and free spins that can increase the odds of winning. The graphics are very simple and colourful.
#7 Pyramid The Quest of Immortality – 96.48%
Let’s go back to Egypt with this slot which reduces the RTP to 96%, but we’re talking about a very respectable percentage. In practice, for every $100 the operator has only $4 on average.
However, always remember to check these percentages as they could possibly change over time.
#8 Jokerizer – fine at 98%
This slot will make you understand how it is not so simple to actually calculate the RTP. In fact, the RTP of Jokerizer varies from 88.8% to 98.0%. It can reach the maximum if the Jokerizer mode remains active. In short, we are potentially facing one of the best slot machines.