Online Casino RNG Guide

Online Casino RNG Guide


A random number generator (RNG) is simply an algorithm that supplies random numbers. The RNG is a device that produces a series of random and unexpected numbers or symbols. Random number generators exist in casinos to make sure that games played are fair and that players are not cheated. In physical and live games, real dealers shuffle cards for randomization. In games like Blackjack, or when dice are rolled, the player knows that the outcomes are totally random. RNGs on the other hand use sophisticated algorithms to make online casino gaming fair.

An RNG is a microprocessor, it is like the brain of the game or slot machine and produces random numbers billions of times per second. RNGs imitate real-life odds so that every spin, die rolled, and cards dealt are random and unpredictable. There are different types of RNGs, online casinos make use of the pseudo-random number generators (PRNG) while physical casinos use hardware random number generators (HRNG).

How RNGs Work

Some physical casino games randomize their games using different methods like card shuffling and dice rolling. Older versions of RNGs were used in lotteries and bingo games. Algorithms were developed as there was an increase in the need for random numbers. Pseudo-random number generators used by casinos do not require an external input to produce an output, it only requires the algorithm and a seed number.

Lengthy strings of random numbers are supplied automatically with this algorithm and are all as a result of a seed number that is fixed. That seed number is used to initialize or start the RNG. The RNG is always in motion, it supplies random numbers every millisecond. It produces a number between 0 and approximately 4 billion, which is then converted into a particular group of numbers which correlates to the symbols on the reels.

RNGs in Online Casinos

RNGs are used in online virtual games without dealers and also used in physical casinos. Physical casinos use them for games like Blackjack, Keno, Video Poker, Roulette games, and other video slot machines. They are also used in classic slots and progressive slots. In slot games, a value is assigned to each symbol on a reel.

The RNG will generate values for each symbol on the reel if the random symbols form a winning combination, the player will be credited accordingly. The RNGs work continuously and stop when a player hits the spin button. The random number is then translated into an outcome like the position of a slot machine reel, the end position of a roulette ball, what number a die shows, or which card is drawn from the deck.

This random number is used as the seed number for the next spin cycle and the cycle continues. Players might wonder what the initial seed number is, but this is unknown to a lot of people as it is a well-protected secret. The seed number has a huge number of digits which makes the algorithm impossible to hack. Since RNGs run continuously, they generate new random numbers and seed numbers per millisecond, making the game even safer.

RNGs allow game software developers to manufacture different exciting games that are fair.  RNGs used by online casinos have regulatory organizations/independent third-party organizations that test the RNG before it is used by an online casino and also inspect the software regularly. These companies also offer consulting services. Online casinos include these certifications on their websites. Some of these testing organizations include:

• Verisign
• Gaming Associates
• iTech LABS
• Technical System Testing

They carry out different tests and some of these tests include:

• penetration testing and full security audits
• game and mathematics evaluations
• random number generator evaluations
• game payout verification and reporting (ongoing RNG)
• poker system audits
• lottery and pari-mutual system evaluations
• live dealer, sportsbook, or betting exchange evaluations

Casinos that pass this suite of tests have met all the requirements like meeting the minimum payouts established by these gaming commissions or by the federal or local laws.

How RNGs Affect Players Strategy

The knowledge that a game is completely random is an important factor in a player’s game strategy. Betting strategies like Martingale used in Roulette can still be used in online games with RNGs, this strategy depends on mathematical principles so the results will be random. Counting strategies cannot work in online games as they depend on finishing a game with a pre-shuffled deck, players have a mental list of the remaining cards in the deck which usually helps in their games. This strategy cannot be used because all card deals are randomized.

No player can predict the next game based on the previous games. Players should avoid committing the “gambler's fallacy”, expecting a jackpot because they haven't gotten one recently. As important as strategy is in any game, the result of the game is still largely dependent on RNGs.

RNGs and RTP

Return to Player (RTP) is the percentage that a slot pays back to players after some number of spins. It is the amount players should get back from games or casinos after a period of time. RNGs are designed to have a specific number of combinations to reach the return to player percentage. Online casinos are expected to watch and constantly supervise the RTPs on their games to ensure that the RNG software is functioning appropriately.

Casinos do this by dividing the total amount of money won by players of a game or slot machine by the total amount of money the game has made. The result of this has to be as close to the stipulated RTP as possible. In situations where there is a huge disparity between the RTP obtained and the expected RTP, casinos are expected to make changes in their RNG settings.

The amount of money a player wins or loses is determined by the RTP and the RTP is determined by the RNG. Understanding how RNGs affect RTP helps players know which online casinos to trust and play at.

Can RNGs Be Cheated?

Theoretically, this can be done but practically, it's virtually impossible as most people simply lack the technical capability to attempt it. RNGs are computer-based and made up of complex algorithms, making them extremely difficult to hack, least of all by players in the casino.

As you may imagine, that it's difficult doesn't mean some people haven't tried to hack casino RNGs. A notable example is Rob Harris, who developed software that predicted RNGs to cheat in the game of Keno, he got away with a lot of money but was later arrested.

Casinos don't bother trying to cheat using RNGs since there is enough money to be gained in the long run and they are also restricted by casino regulators. The regular testing of RNGs now makes it doubly difficult for it to be hacked by both players and casinos hoping to rig it for their benefit.

It's worth noting that some fraudulent companies have copied popular games from legitimate casinos and game software developers and tweaked their RNG software to rake in excessive earnings. Whenever players play in these online casinos, they inevitably lose. This is why players are encouraged to play with properly licensed and regulated casinos that have been assessed for fair play and will be open to regular audits.


Random number generators make games played in casinos (both online and physical) fair and have also made online gaming easier. Without the stress of making sure games are fair and players not cheated, game developers can direct their efforts to make sure their games are fun, engaging, and have better aesthetics.

New FanDuel Casino customers get to play your first day risk-free up to $200 when you sign up today!