Before a slot, roulette wheel, or video poker game can take real money, its random number generator has to pass an independent lab's statistical tests — a requirement written into the UK Gambling Commission's remote gambling technical standards (RTS 7), in force since February 2021 and last updated in May 2024, and mirrored by licensing regimes worldwide.
What Does "RNG Certified" Actually Mean?
An RNG — the random number generator — is the piece of software that decides which card, symbol, or number comes up next. "Certified" means an independent testing lab has checked that generator against a written technical standard and confirmed it behaves the way the game's published rules say it does. Under the UK Gambling Commission's RTS 7, that means random number generation and game results must be, in the regulator's own words, "acceptably random," a claim the operator has to demonstrate through statistical analysis rather than simply assert, per the Gambling Commission's remote gambling and software technical standards.
Who Tests a Game's RNG Before It Goes Live?
Regulators generally do not run the tests themselves. They require licensees to use accredited independent test houses. Gaming Laboratories International (GLI) is one of the labs game studios submit to: its published RNG submission requirements, built around its GLI-11 standard, call for the test application to match production code as closely as possible, along with source code documentation, checksums, and both raw and final-outcome data sets for the lab to run its analysis against, per GLI's technical specifications for RNG testing. That requirement to match production code matters: a lab is not evaluating a simplified demo of the generator, it is evaluating the same logic that will decide real bets, which is why studios have to hand over checksums that prove the submitted build and the shipped build are the same file. eCOGRA is another accredited option; its published RNG service describes testing carried out by in-house mathematicians using "statistically sound" methods to confirm outcomes are independent and unbiased, and states that its certification is used to meet regulatory standards in jurisdictions including Great Britain, the Netherlands, and Spain, per eCOGRA's own RNG testing and certification page. A studio launching into several regulated markets at once will often need sign-off from more than one lab, since a certification issued for one jurisdiction's standard does not automatically satisfy another's licensing body.
What Must the RNG Prove to Pass?
The UK Gambling Commission's standard sets out specific, checkable properties rather than a vague promise of fairness. Per RTS Requirement 7A, a compliant RNG must produce output that is uniformly distributed and matches the game's theoretical probabilities, must stay unpredictable to anyone without knowledge of the algorithm and its seed, must not cycle or fall into sync across multiple instances of the same generator, and must not let its seeding process introduce hidden predictability. The standard is explicit on one point players often assume the other way: "adaptive behaviour (that is, a compensated game) is not permitted" — a machine cannot secretly tighten or loosen up to chase a target payout percentage over time, per the Gambling Commission's RTS 7.
Two further requirements protect what the player actually sees. RTS Requirement 7B requires that random numbers be used in the order they are generated, without discarding results to steer toward a different outcome, and that the game apply its own stated rules and payouts consistently. RTS Requirement 7C bars any design "reasonably expected to mislead the customer about the likelihood of particular results" — the standard specifically calls out near-miss effects, where a game visually suggests a player almost won when the underlying probability was never close, per the Gambling Commission's technical standards.
Does Certification Mean the Game Stays Fair Forever?
Certification is a snapshot of the software that was submitted, not a permanent guarantee. RTS Requirement 7D addresses this directly: an operator cannot change a game's rules while a round or game instance is still active, except in ways the stated rules already allow, and any alteration to the rules has to be communicated to the customer, per the Gambling Commission's RTS 7. In practice, this is why a meaningful RNG change — a new bonus feature, an adjusted paytable, a math model update — triggers a fresh submission to the testing lab rather than being pushed live quietly. The certification travels with the specific, versioned build of the game, not with the game's name.
Why Bother Checking for RNG Certification at All?
Most players never see a certification mark, and licensed sites are not required to explain the process on the page where the game loads. But the underlying paperwork is usually traceable: a licensed operator's terms or footer will typically name its jurisdiction, and that jurisdiction's regulator publishes the technical standard its games must meet — in the UK's case, the same RTS 7 requirements detailed above. Knowing what those requirements actually cover is what turns "certified" from a badge into something checkable: a specific set of behaviors — no compensation, no discarded draws, no misleading near-misses, no live rule changes — that a named lab tested a named, versioned build against.
What This Means for the Player
RNG certification answers a narrow question: does this generator behave randomly, and does the game use its output the way the rules say it will. It does not set the house edge, does not promise a particular payout percentage, and does not mean any individual session will win or lose — a certified RNG can still produce a long losing streak, because that outcome is exactly what genuine randomness looks like over a short sample. What certification does rule out is a game secretly compensating results, discarding unfavorable draws, or dangling a near-miss that was never really close — the specific behaviors the Gambling Commission's, GLI's, and eCOGRA's standards were written to catch.
Frequently Asked Questions
For a related xbox perspective, read Why Xbox Casino Games Never Pay Out Real Money.