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RNG

A random number generator — software that ensures every spin’s and card deal’s outcome is random and independent.

Also: random number generator · random number generator

Definition

The RNG, or random number generator, is an algorithm that determines casino game outcomes. Every spin, card and dice roll is based on a number the generator outputs, independent of previous results or bet size.

The RNGs of licensed casinos’ games are tested by independent labs such as eCOGRA, iTech Labs and GLI, which verify that results are statistically random and the RTP matches what’s declared. In a live casino, physical randomness replaces the software RNG: real cards, roulette and dice.

Related and sources

See also RTP and SSL encryption. Source: Random number generation (Wikipedia).

Quick facts

eCOGRA, iTech Labs, GLITesters
Independent of previous onesEach result
Physical randomnessIn a live casino

Example: a slot machine generates thousands of numbers per second even when no one is playing. At the moment of the press the current value is taken, which determines the outcome — pressing a second earlier or later would give a different result.

How does an RNG work?

1

Number generation

The algorithm continuously outputs pseudo-random numbers from a continuously changing seed.

2

Determining the result

The number taken at the moment of the spin is converted into the game result — symbols, cards or numbers.

3

Independence

Each result is independent of previous ones: the machine remembers no wins or losses.

4

Certification

Independent labs test the generator with millions of simulations and issue a certificate.

Frequently asked questions

Can a slot machine be “hot” or “cold”?

No. Each spin is independent and the machine doesn’t know how much it has paid out recently. The feeling of a hot or cold machine is a perception error described by the gambler’s fallacy.

Can an RNG be outsmarted?

In a licensed casino, no. The generator is certified and server-side — your playing pattern, the time of day or the rhythm of bets don’t affect the results.

How do I know a casino’s RNG is fair?

Choose a licensed casino and games from well-known studios. A licence requires using a certified RNG, and audits check it regularly.

Guide

RNG (Random Number Generator): the engine behind fair casino games

An RNG, or Random Number Generator, is the software algorithm that continuously produces streams of numbers at enormous speed, and those numbers decide which symbol lands on a slot reel, which card the virtual dealer turns over and where the roulette ball settles. Unlike the old mechanical machines whose outcome depended on physical reels, every result in a modern online casino is calculated in a fraction of a second. When you press the spin button, the system does not look at the size of your bet or your recent losses — it simply captures the exact moment you clicked and converts it into a pre-generated number. That is why each spin is completely independent of the one before it.

For a player in Estonia, the trustworthiness of an RNG is tied directly to whether the casino operates under a licence issued by the Estonian Tax and Customs Board (EMTA). Operators licensed to work in Estonia are required to use certified generators whose fairness is verified by independent testing laboratories. These labs analyse millions of simulated outcomes to confirm that the distribution really is even and unpredictable. This is exactly why there is a vast safety gap between a licensed casino and some unknown, unvetted platform: with an uncertified RNG a player has no guarantee whatsoever that the game is fair.

In practice most online-casino generators rely on what is called a pseudo-random algorithm (PRNG). The numbers are produced by a mathematical formula that starts from an initial value known as the seed. Although the sequence is technically deterministic, it is so long and complex that predicting or influencing the outcome is effectively impossible for a human. Well-built systems constantly refresh the seed using unpredictable inputs, so even someone who understands the system could not calculate the next result.

RNG is closely linked to RTP (return to player) and volatility, but the three should not be confused. The RNG guarantees the randomness of individual outcomes, while RTP describes the theoretical average payout over a very long run of play. In the short term, randomness can create both long winning streaks and painful losing streaks — neither of which means a game has turned "hot" or "cold."

The most common misconception is the so-called gambler's fallacy: the belief that a win is "due" after a run of losses, or that a machine which has not paid out for a while is "ready" to do so. Because every outcome is independent, the RNG remembers none of your previous spins and owes you nothing. No pattern, time of day or betting system can outwit the generator. For that reason it is wise to treat play strictly as entertainment rather than a source of income: set yourself a time and money limit in advance, play only at EMTA-licensed casinos, remember that gambling in Estonia is permitted from the age of 21, and if the game stops being fun, reach out to Estonia's responsible-gambling support services.