Online casino algorithms: RTP, random numbers and odds. How do they work?

At first glance, acronyms like RTP or RNG may seem insignificant. Or, they can give the idea of ​​concealing complicated and difficult to understand concepts. So let’s try to explain what they are and why they are important when playing in online casinos

It is known that luck helps in playing. However, that’s not the only thing that matters. When sitting in front of a slot machine, roulette or poker table, it can be very useful to have some knowledge of chance. Playing exclusively on intuition, in fact, most of the time does not pay.

In this regard, there is another element that online casino enthusiasts need to keep in mind. This is theRTP, acronym that stands for return to player (in Italian, return to the player). But let’s see more specifically what it is.

RTP: what is the return to the player

Let’s start by saying why it is important to know the concept of RTP. The matter is soon explained. The return to the player, otherwise known as payout percentage, is an indicator of the possibility and amount of payout.

As shown your, RTP is one of the strengths of the best online casinos. In addition to offering a great variety of games (there must always be roulette, slot machines, blackjack) and titles, the most successful operators are those who offer Higher RTPs.

The return to the player is indicated with a percentage number. This number represents as a percentage the amount of money returned to the player in the event of a win compared to the total income. Let’s try to make a practical example to make the concept more understandable.

Let’s imagine playing a slot with 96% RTP and to have one thousand euros available. If we decide to play a thousand plays for one euro each, the machine should give us back 960 euros out of a thousand cashed. On our betting cycle, the provider would then earn 4% (the opposite of the RTP).

Online casinos are obliged to report the average return on their games, which is always less than 100%. The best slot machines generally have an RTP of around 96%. The one of the top roulette is instead 97% (98% for the best blackjack tables).

For completeness of the information, it is good to remember that the payout teorico it is calculated on the overall game sessions, and not on those performed by a single player.

The volatility of slot machines

When playing roulette and online slot machines, however, there is another parameter to consider: that of volatility. Casino game providers express this in qualitative terms as “high” or “low”.

Volatility simply describes the riskiness of a given game in terms of the frequency and size of the payout. Games with high volatility, generally considered riskier, are the ones that promise bigger winnings, but a lower frequency of winning combinations (you win less often, with a higher probability of losing the stakes). The risk to players decreases in products with low volatility, where the favorable combinations they are more frequent but the amounts won are indisputably lower.

RNG: what is the random number generator

Another aspect that you need to be aware of when you are preparing to play online concerns randomness. The casino games present on the net are in fact governed by a sort of central brain called RNG (random number generator).

Simply put, RNG is an algorithm that works through software. Its function is to guarantee the randomness of combinations and winnings, to ensure that those that occurred previously do not affect the subsequent ones in any way. This means that when we push a slot machine button, throw a roulette ball or shuffle a deck of cards, we will have no way of predicting the outcome of our action.

Each casino game uses a different random number generator. The regularity of the bets depends on its correct functioning, but also the reliability and the security of an online casino. Precisely to guarantee this, it is necessary that the programs through which the RNGs work are made inaccessible and protected from any external form of intrusion.

To be sure of the seriousness of an operator it is essential to make sure that it is in possession of regular ADM license (formerly AAMS). In fact, the Italian state only issues it to providers who use safe and regular RNGs, to guarantee the integrity and honesty of the services offered. Supervision by a state body (in this case by the Customs and Monopolies Agency) is the best guarantee for users of virtual gambling halls.


A good understanding of randomness, probability, risk and volatility allows you to better understand how online casinos work. At the same time, it allows us to consciously play the game we choose, aware of what are the real advantages of the house and our chances of winning.