RNG stands for Random Number Generator: the software that determines the outcome of each play in casino games. Every spin, card, or number comes from a sequence generated by an algorithm, with neither the operator nor the player able to influence it.
The RNG is used in slot machines, digital roulette, automated blackjack, video poker, and other games without a real dealer. Last updated: July 2026.
How the RNG works in casino games
The RNG continuously generates thousands of numeric combinations per second, even when no one is playing. At the exact moment you press to spin a slot or start a hand, the system takes the combination available at that instant and derives the result you see on the screen from it.
It is a pseudo-random algorithm: it starts from an initial value, called a seed, and produces from it a sequence that passes statistical tests of randomness and cannot be predicted or reproduced from outside. This is the same type of system that independent laboratories audit.
Why each round is independent of the previous one
Each result generated by the RNG is independent of all previous ones: the system does not remember what happened in previous spins. A slot machine that has not paid out for a long time does not have a higher probability of paying on the next spin, and one that just paid out does not have a lower probability.
This means there are no "hot" or "cold" machines, no streaks that can be anticipated, and no more favorable times of day. Any strategy based on the history of results is based on a premise that the RNG does not fulfill, since the probability of each play is exactly the same at the beginning and at the end of a session.
What the RNG guarantees and what it does not guarantee
The RNG guarantees that the outcome of each play is unpredictable and that two players in the same game face the same odds. It does not guarantee that all games pay out equally or that a session ends in a win.
| What the RNG does ensure | What the RNG does not change |
|---|---|
| That the outcome is not decided by the operator | The RTP of each game, which is different for each title |
| That the outcome cannot be altered by the player | The house edge built into the rules |
| That each round is independent of the previous one | That in the long run the game has a negative expected result for the player |
| That two players in the same game have the same probability | That a specific session can end in a loss |
The RTP (return to player percentage) of each game appears in its information sheet and is a different figure from the RNG: the RNG distributes results randomly, and the RTP defines how the game is configured in the long term.
Who certifies that the RNG works correctly
RNGs on regulated platforms are audited by accredited independent testing laboratories such as eCOGRA, GLI (Gaming Laboratories International), or iTech Labs, which analyze millions of results to verify that the distribution is statistically random and matches the declared RTP.
Gaming authorities in each country require this certification as a condition to grant and maintain licenses, and laboratories repeat the tests periodically. Any modification to the game software requires a new certification before it can be put into operation.
Which games use RNG and which do not
The RNG determines the outcome in all games without a real dealer: slot machines, digital roulette, automated blackjack, video poker, electronic table games, and instant games.
Live Casino tables with a real dealer do not use RNG because the outcome is produced by a physical element: a real roulette wheel, a physical deck of cards, or dice. In those tables, randomness depends on the equipment and the studio procedures, which are audited separately. Some Live Casino games with automated elements do incorporate RNG in specific parts of the round, and in that case, it is indicated in the game rules.