- The RNG runs continuously and is sampled at spin time, so the exact millisecond of your press selects the result.
- Most slots use pseudo-random generators, deterministic algorithms that are unpredictable in practice, not true hardware randomness.
- Each spin is independent of previous spins in fully random games, which includes online slots under GB remote and Ontario standards.
- Some physical gaming machines in Great Britain may use compensated games that slightly adjust odds based on recent payouts, but compensated behaviour is banned for remote online play in Great Britain.
- Regulators require RNGs to be uniformly distributed, unpredictable and independently tested by labs such as GLI and eCOGRA before release.
Yes, the outcome is sampled from a continuously running Random Number Generator at or near the moment you press spin, but it is not pre-stored. Most slots use pseudo-random algorithms that are deterministic yet practically unpredictable, not true physical randomness, and each spin is independent in fully random games.
How the RNG Decides the Outcome at Spin Time
The outcome is not queued or predetermined long before you play. The RNG runs continuously, even when the game is not being played, and the process is instantaneous and ensures each game result is independent of previous results. When you spin the reels, the RNG software chooses numbers or symbols completely at random and independently of any previous spin.
Because the generator is always cycling, the precise moment the game samples it on your spin trigger effectively determines the result. This continuous operation is what makes timing unpredictable to the player, and regulators require that random numbers are used in the order received and not discarded to influence results.
Sources: Ensuring Fair Play with RNG Testing and eCOGRA Certification; How can I be sure the RNG in any game is actually random and fair?; Remote gambling and software technical standards (RTS) – RTS 7 – Generation of random outcomes.
Pseudo-Random Versus Truly Random
Random usually means pseudo random with regard to gaming machine outcomes. Pseudo-random number generators use algorithms to produce sequences that appear random but are determined by an initial seed value, and they will repeat the same sequence if given the same seed.
True random number generators generate numbers that are genuinely random and unpredictable and rely on physical processes such as atmospheric noise or radioactive decay, rather than algorithms or seed values. The seed for a pseudo-random algorithm can be derived from the current time, mouse movements or other data, and periodic re-seeding helps maintain unpredictability. Both UK Gambling Commission and Ontario standards require that output be statistically independent, uniformly distributed and computationally infeasible to predict even with knowledge of the algorithm.
Sources: LA Bulletin August 2020 – Feature article How can gaming machines meet their %RTP if they are random?; Random Number Generator – GLI; Ensuring Fair Play with RNG Testing and eCOGRA Certification; Regulatory returns guidance – 2 – Random number generation – Casino equipment technical requirements; 21. Random Number Generator (RNG) | Alcohol and Gaming Commission of Ontario.
Fully Random vs Compensated Games
Gaming machines achieve their stated return to player in one of two ways, which creates an important regulatory distinction. Fully random games rely purely on statistical chance over millions of cycles, while compensated games include an additional control element.
A compensated game constantly checks how much has been awarded recently and, knowing the current and target percentage, will slightly vary the odds of a win or the value of a win for the subsequent series of games. This is done to give a less volatile experience and to make complex high-tech style games with multiple player choices more able to meet targets. Compensated games typically reach their target in tens or hundreds of thousands of cycles, while fully random games need a million or more cycles.
Hypothetical illustrative example based on supplied evidence: a 3-reel fruit machine with 20 positions per reel has 8000 possible display combinations. If the designer places 2 Bar symbols on each reel, there are 8 chances in 8000 of three Bars. At 50p per game, 8000 games cost 4000 pounds. If winning combinations pay a total of 3600 pounds across those 8000 theoretical outcomes, the return is 90 percent. This is a hypothetical calculation to show how designers tune symbol counts and pay values to set return, and in a fully random version the actual return would still vary considerably over only 8000 plays and only average out over very many games.
For players this distinction matters. Compensated behaviour is not permitted for remote gambling in Great Britain, and Ontario requires that RNG output must not be dependent on amount wagered, style or method of play. Compensated games are permitted only on some non-remote physical machines under the Great Britain description, not for online slots under those standards.
| Type | How Return Is Controlled | Independence of Each Spin |
|---|---|---|
| Fully random | Pure statistical probability over millions of spins | Each spin fully independent |
| Compensated | Software slightly adjusts win odds or win values based on recent payout history | Probabilities can be subtly adjusted, not fully independent |
Sources: LA Bulletin August 2020 – Feature article How can gaming machines meet their %RTP if they are random?; Remote gambling and software technical standards (RTS) – RTS 7 – Generation of random outcomes; 21. Random Number Generator (RNG) | Alcohol and Gaming Commission of Ontario.
Regulation, Testing and Why Past Spins Do Not Influence the Next
All sources that address independence agree that in fully random games past results do not influence future results, which refutes beliefs such as a machine being due for a win. Standards require the RNG output to be unpredictable, uniformly distributed, non-cycling and unaffected by seeding patterns, and to pass recognised statistical tests for frequency, runs and serial correlation within a 99 percent confidence interval.
Before release, independent testing labs such as GLI and eCOGRA rigorously test and certify RNGs to meet stringent standards, with simulations running billions of simulated games to verify that return and outcome distribution match the design and that hardware and software meet jurisdictional requirements including metering, non-volatile memory and interruption recovery.
Sources: How can I be sure the RNG in any game is actually random and fair?; Ensuring Fair Play with RNG Testing and eCOGRA Certification; Remote gambling and software technical standards (RTS) – RTS 7 – Generation of random outcomes; 21. Random Number Generator (RNG) | Alcohol and Gaming Commission of Ontario; Regulatory returns guidance – 2 – Random number generation – Casino equipment technical requirements; How Casino Games are Tested – GLI.
Sources and further reading
- Ensuring Fair Play with RNG Testing and eCOGRA Certification
- How can I be sure the RNG in any game is actually random and fair?
- Remote gambling and software technical standards (RTS) – RTS 7 – Generation of random outcomes
- LA Bulletin August 2020 – Feature article How can gaming machines meet their %RTP if they are random?
- Random Number Generator – GLI
- Regulatory returns guidance – 2 – Random number generation – Casino equipment technical requirements
- 21. Random Number Generator (RNG) | Alcohol and Gaming Commission of Ontario
- How Casino Games are Tested – GLI
Community questions behind this article
These discussions helped identify the question. Player comments are not used as evidence for game rules or odds.
Prepared with AI assistance and automated checks against the cited research brief. Human review is not implied. Source research date: 2026-09-22.
Frequently Asked Questions
Does the slot know if it just paid a jackpot and will avoid paying again?
In fully random games, which include online slots regulated as remote gambling in Great Britain and cGaming in Ontario, no. Each spin is independent and the RNG output must not exhibit detectable patterns or be dependent on previous output or wager style.
Is pressing the button faster or at a certain time a strategy to win?
No. Because the RNG runs continuously and is sampled at spin time, the outcome is determined by an unpredictable moment and regulators require unpredictability and uniform distribution. No timing pattern can influence a compliant fully random game.
