How does rng work in online casino games?

How Does Rng Work At Casinos?

Random number generation, or RNG, is a core component of many video games. But while it is easy to see how a true random number generator can work in a computer game, how does RNG work in online gaming? And what purpose do they serve in game development? This article will explore the inner workings of RNG and explain why it is one of the most important elements of casino game design.


Players who have spun a few slots before would know that the iGaming world is packed with unpredictable data. No player can truly know when they’re going to win or if they’re going to win at all, and that is all thanks to a mechanic used to randomly generate numbers. 

Whether you have seen an RNG in action in a video game, or this is the very first time you’re hearing of a mechanic like this, allow us to break it all down.


As its name implies, a random number generator is a mechanic or application that relies on mathematical formulas to generate a random result. Many players believe RNGs to be a by-product of today’s modern computer programming skills, but they actually go back pretty far into the past. 

Randomness devices have existed since ancient times, be it in the form of coin flipping, straw drawing, dice rolling or card shuffling. The only difference between these forms of RNGs and today’s deterministic computation programmes is that a true random number generator cannot rely on mathematical equations to produce a truly random number. If an equation is involved, then it cannot be considered random.

For this reason, many of today’s random number generators are actually pseudo-random number generators since the seed value is known, and so the output can be predicted, but they are sufficient enough to fulfil most tasks as true randomness is not required all the time — a slot machine only appears random. 


Random number generators use a variety of algorithms to generate random numbers that are incorporated in online slot games. One RNG algorithm can be more sophisticated than the other, but all rely on a set of principles that ensure the resulting numbers are true random numbers. 

One such principle is called entropy. Entropy is a measure of how unpredictable a set of data is. The higher the entropy, the more random the data is. The RNG will draw from a data pool with high entropy to generate a random number. This pool is constantly refreshed, guaranteeing that the generated numbers are always unique.

Another important principle is called seeding. Seeding ensures that each time the RNG generates a new set of random numbers, it does so in a unique way. This prevents the same sequence of numbers from being generated twice. With a different seed value, random number generators can produce billions of unique sequences of true random numbers — unless, of course, you’re working with true random number generators.

A TRNG does not need a seed to operate as TRNGs are digital snapshots of thermal or atmospheric noise and electromagnetic pulses — but we’ll get into that later.

These principles are at the very core of casino game development. RNGs guarantee that all outcomes of reel spins, digital dice rolls or card draws are unpredictable. This means that all players have an equal chance of winning — and losing. That is precisely why it’s important to only play at licensed online casinos that partner with licensed game providers. Operators and providers offering services under reputable licences guarantee that the games are safe and fair in every aspect. 


To truly wrap our heads around how an RNG can produce totally random data, let’s take a look at how a random generator actually works by comparing it to the RTP:


RTP (Return to Player) is a percentage value representing the theoretical return of an online casino game if played over infinite time. It is usually around 96-98% for most online slot games, for example. The rest is considered the casino’s income, as it compensates for any potential losses and covers all operating costs, such as staff salaries, RNG testing and other expenses. 

In online slots, the RTP is a statistical average obtained over millions of spins. This statistic is hardwired into the game, and providers must pass all audits and inspections that test the game’s fairness and RTP accuracy. This is where RNGs come into play, as they directly influence the randomness of all game outcomes, like the frequency and size of wins.

Similarly to the RTP, the house edge represents the casino’s advantage over the player in a given game. For example, an RTP of 98% is the same as a house edge of 2%; however, the house edge is often used in the context of live games. In part, that’s because the house edge can increase or decrease in table and card games depending on the player’s in-game decisions. As more and more variants of these games pop up, you’ll notice that many providers will opt to express the house advantage as an RTP, particularly in regards to side bets. 


Before we dive in and explore randomness in online casino games, let’s take a closer look at the different types of random number generators out there.

There are two main categories of RNG: hardware RNG and software RNG. Hardware random number generators are physical devices that generate random numbers. There are many different types of hardware RNG, but they all have one common goal: to generate random numbers. These random numbers can be used for various purposes, such as generating cryptographic keys, picking lottery numbers, simulating random events or determining which symbols will fall on the reels of your favourite slot. Hardware RNG can be divided into two main categories: true random number generators (TRNGs) and pseudo-random number generators (PRNGs).

A software random number generator is a computer program that generates random numbers. There are several types of software RNGs as well; they are generally PRNGs, meaning that software RNG relies on algorithms to mimic the selection of a value to approximate true randomness.  Take an cryptographically-secure pseudorandom number generator (CSPRNG), for example. CSPRNGs extract random numbers from physical events taking place in a game and encode them with a hash function that is suitable for cryptography. Then, it will act like any pseudo-random number generator.

Circling back to what we discussed earlier, a pseudo-random generator cannot produce truly random numbers but pseudo-random numbers.


Random number generators play a vital role in the design of every casino game. They are responsible for generating random numbers that can be used in various ways, from creating variability and unpredictability to simulating realistic gameplay. RNGs draw from their pool of high entropy data to generate each number, ensuring that the resulting sequence is both unpredictable and unique. By utilising different seeds, RNGs create countless possibilities for new sequences, meaning that every player stands an equal chance of winning.


Along with online slots, RNG table games are another great example of random number generators in action. RNG table games rely on the output of an algorithm. In a sense, you’re playing against the algorithm when you play at an RNG table.


In Live Casino games, the live dealer generates all card draws, wheel spins, and dice rolls.

The way these games work is that each RNG wheel spin or hand has its own, truly random seed and outcome: the random number generator doesn’t “look ahead” to see what will happen next and adjust outputs accordingly. No matter how often you play roulette with the same bets, each wheel spin will be independent and unpredictable.


Online RNGs, also referred to as pseudo-random number generators are pretty complex. Although the numbers generated aren’t truly random numbers, RNGs feature elaborate mathematical codes that are buried in software and encryption. On top of that, many providers monitor their RNGs with hidden cameras, so it is almost impossible to cheat an online random number generator — almost.

Since RNGs are repeated calls to function, in reality, all you need is a key or cypher to decode the algorithm; also known as a seed. Once the seed is found, a hacker can substitute pseudo-random bits for more predictable numbers.

With that said, however, it is much easier said than done. Providers fight tooth and nail to ensure their games have the most extensive protocols installed by employing a large handful of defensive strategies.



Yes. Online casinos utilise online RNGs, also referred to as pseudo-random number generators, to randomly generate a set of sequences or winning numbers every time players give the game a spin. A random number generator is not only used for online slot games but for Live Casino games and table games as well.


The way pseudo-random number generators work is it will produce a random sequence of symbols every time you spin the reels. Random number generation, as its name implies, is completely unpredictable to a certain extent, so there is no way to guarantee a win as you play.


Although a random number generator relies on a set of repeated calls to function, in reality, all you need is a key or cypher to decode the algorithm and replace it with less-random data.

With that said, however, providers install the most extensive protocols by employing a large handful of defensive strategies, so it is a lot easier said than done.


For the most part, RNGs are totally fair — if you’re playing at a licensed online casino, that partnered with licensed game providers. Operators and providers offering services under reputable licences guarantee that the games are safe and fair in every aspect.

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