JeffBet by Matthew Gover |
Date of Publishing: 17 May 2023

5/5 - (10 votes)

Random Number Generator (RNG) in Slots


A random number generator is an algorithm or software designed to determine outcomes in digital games. Such software ensures that the outcomes generated are random and without bias. Newer slot machines are equipped with microchips that can generate number combinations at random. 

The complex algorithm generates numerical sequences that determine the position of reels in slot machines and casino games. Casino operators are developing games by integrating the latest random number generation technologies. This article will cover everything about random number generators (RNG) in slots.

History of RNG in Slot Machines

Before online casinos were a thing, mechanical slot machines were popular. These included a lever that the players pulled, and the outcome was determined by mechanical reels. It was in the 1940s that John von Neumann invented the random number generator. Gaming operators then used the software to introduce online casino games. 

Since their inception, pseudo-random number generators have gone through many developments and upgrades. Today’s algorithms use a tiny computer chip to spin the reels, ensuring that each spin is entirely random and fair. They take up very little space and memory and can choose from vast sequences of more than a billion numbers.

How do RNGs work?

The RNG is essentially a microprocessor that uses random numbers to determine the position of reels in slots. There are two methods used for random number generation. True random number generators take entropy or actual randomness into account, while pseudo-random number generators are unaffected by natural entropy. Slot games utilise a pseudo-random number generator to determine the outcome.

Since pseudo-random numbers are not based on actual randomness, some people think they are unfair. This is not the case because gaming developers use a computer-generated seed value to generate random outcomes efficiently. Pseudo-random generators are a cost-efficient option as compared to their true counterparts.

The seed number serves as the base value of the random number generator algorithm. A system clock selects the seed, designed to imitate natural entropy. This ensures that a slot game’s physical reels are spun randomly. 

RNG and Game Outcomes

Each reel in a slot machine has game symbols, and the exact number of symbols differs among slots. The random number generator (RNG) assigns a specific value to each symbol. When a player clicks the spin button, one value is chosen randomly. The number selected determines the symbol at each reel independently. If the symbols create a winning combination, the player will receive their winnings accordingly. 

The payout frequency and ratio are programmed for each slot and cannot be changed. The payout frequency is the probability of landing a winning combination, and it can range from high to extremely low. A high frequency means the slot is more likely to land a winning combination.

The payout ratio is the average amount of money returned to players compared to the amount wagered. The common term for this is the return to player (RTP). Casino sites want a consistent RTP, and the number generator is programmed to select certain combinations to achieve this. Low volatility slots tend to have higher RTPs, and both are affected by the programming of the computer program. 


RNG Certification and Regulation

It is essential for every licensed casino to have an RNG certification. Each reputable casino is licensed and certified by authorities, and you can simply check this on their website. This certification provides high security to the software and algorithm used and prevents third parties from tampering with it.

The regulatory body in each country provides the certification of RNG. For the UK, this is the UK Gambling Commission, which provides the certification by ensuring that the online slot randomly generates outcomes. The casino control board uses the services of third parties to check the randomness and fairness of online casinos. 

The audits check different factors, including game and mathematical evaluations, game payout verification, live dealer games, and other inspections that ensure that licensed casinos are bias-free. This ensures that the numbers generated are based on complete randomness. 

Common RNG Myths and Misconceptions

Due to a lack of knowledge about their working mechanism, some myths and misconceptions have been circulating regarding random number generators. Some of the most common ones have been discussed and debunked below:

Slot Machines Have Hot and Cold Cycles

Some players believe that slot machines have extended wins or losses. Frequent wins are called hot cycles, while frequent losses are called cold cycles. The truth is that there is no such thing as predetermined patterns because RNGs generate numbers at random, and each symbol has an equal probability of being selected.

Players Can Predict the Next Outcome

Some people think that players can predict the next outcome based on previous spins. This is not possible, though, because the algorithm is designed to randomly select a new number of each spin, which has no relationship with the previous spins.

Casino Operators Can Manipulate RNG

A few players blame their inability to win on casino operators, stating that they can manipulate the software and reduce the chances of winning for players. The truth is that casino developers are subject to strict regulations by the internal state, which uses testing laboratories and technical systems testing to ensure that RNGs produce unbiased and random results.

Player Strategies for RNG-Based Games

Remember that random number generators are fair; no such strategy can ensure a win each time. Still, players can employ a few strategies to enhance their overall slot experience. 

Managing Bankroll Effectively

Managing your bankroll efficiently is important to avoid huge losses. You can set limits on your budget before you play and ensure you don’t exceed your budget under any circumstance. This can help keep your losses controlled and also prevent chances of problem gambling issues like addiction.

Understanding the Importance of RTP and Volatility

Watch for the RTP and volatility of the slot games you want to play. The RTP can determine the long-term payout of the game, so make sure you select one with an RTP higher than 95%. Volatility will measure the risk and reward associated with a game. Low volatility slots are ideal for risk-averse people, while high volatility slots are suitable for risk-takers.

Embracing the Random Nature of Casino Games

Remember that the outcomes of casino games are based on a random result, so factors like RTP, house edge, and volatility cannot guarantee a win. View the game as entertainment and not as a source of income, allowing you to enjoy the gameplay entirely. 

RNG in Other Casino Games

Just like slot machines, RNGs also play a significant role in table games and video poker. In table games like blackjack and roulette, an RNG is responsible for determining the outcomes of virtual simulations. These can include the cards being dealt, the roulette wheel position, and the consequence of a dice roll. Video poker also relies on RNGs to determine which playing cards will be drawn, and the paytable will determine the payout. 

The purpose of live dealer games is to mimic a land-based casino where physical events with real-time human dealers take place. Here, random number generation determines the outcomes of card shuffling and dealing. So, casino games utilise RNGs in the same way as online slots.


Random number generators play a critical role in ensuring that casino games are fair and free from any manipulation and predictability. The presence of regulatory bodies ensures that the outcomes of online slots are based on chance. Frequent audits are carried out, allowing players to have peace of mind that the slots they are playing are fair. 

When players understand RNGs well, they can make better-informed gaming decisions. If players focus on good bankroll management, they are less likely to believe in myths about manipulations and predictions. Other gaming decisions can include setting reasonable goals and enjoying the game instead of trying to predict its outcome. 

About the Author

Author: Matthew Gover.

After graduating, Matthew began working as an English teacher abroad, initially in Spain and then Vietnam before finally coming back to the UK to settle. Matthew has always had a love for writing and an even bigger love for the igaming industry... Read More

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