RTP at Non-GamStop Casinos: Are Payout Percentages Really Higher?

Every month I receive emails from readers asking essentially the same question: “Do non-GamStop casinos really have better RTPs?” The short answer is — it depends. The longer answer involves understanding what RTP actually measures, how game providers configure it differently across jurisdictions, and why the number displayed in a game’s help file might not match the number running on the server. After nine years of analysing offshore gambling, RTP remains the single most misunderstood metric in the industry.

RTP, House Edge, and Variance: Quick Primer

Before we compare anything, the terminology needs to be clear. RTP — Return to Player — is the theoretical percentage of all wagered money that a game pays back to players over time. A slot with 96% RTP returns £96 for every £100 wagered, on average, over millions of spins. The remaining 4% is the house edge — the operator’s theoretical profit margin.

Two critical words in that definition: “theoretical” and “over time.” RTP is not a session-by-session guarantee. It is a statistical average calculated across an effectively infinite number of rounds. In a single session, your actual return might be 0% or 500%. Variance — sometimes called volatility — measures how much individual results deviate from the theoretical average. A high-variance slot pays out less frequently but in larger amounts; a low-variance slot pays more often but in smaller amounts. Both can have identical RTPs.

The distinction matters because players often conflate RTP with their subjective experience. A 96% RTP slot that pays nothing for 200 spins and then delivers a 500x win feels different from a 94% RTP slot that trickles out small wins every ten spins — but the higher-RTP game can produce the worse session outcome. RTP tells you about long-term mathematical expectation, not about what will happen in the next hour.

House edge is simply 100% minus RTP. A 96% RTP game has a 4% house edge. This is the casino’s theoretical take on every pound wagered. When comparing UKGC and offshore casinos, the difference in house edge between a 96.5% game and a 94% game is 2.5 percentage points — which translates to losing an additional £2.50 per £100 wagered. Over a session of 500 spins at £1 each, that is the difference between an expected loss of £17.50 and £30.

UKGC vs. Offshore RTP: Where the Differences Lie

I spent two weeks last year running a controlled comparison. I loaded the same ten slot titles from the same providers at a UKGC-licensed casino and at two Curaçao-licensed non-GamStop casinos. Then I checked the RTP displayed in each game’s information panel.

The results were mixed. For six of the ten titles, the RTP was identical across all three casinos. For three titles, the non-GamStop versions showed an RTP 0.5-1.5 percentage points higher than the UKGC version. For one title, the UKGC version actually had a marginally higher RTP than the offshore deployment. The claim that non-GamStop casinos universally offer better RTPs is not supported by the data. Some games are higher, some are the same, and occasionally one is lower.

The broader market data adds context. Slot GGY at UKGC sites in Q1 2026 was £773 million from 25.1 billion spins — an implied average loss per spin that is consistent with RTPs in the 95-97% range. The UKGC does not mandate a minimum RTP, but it requires operators to display RTP information and to use independently tested random number generators. The practical floor at UKGC sites tends to be around 94%, because operators know that players can check and compare.

At non-GamStop casinos, there is no mandatory RTP disclosure. Some operators display RTP prominently; others bury it or omit it entirely. The absence of a regulatory minimum means that some offshore operators run games at the provider’s lowest available RTP tier — which can drop to 87-90% on certain titles. Without checking, you have no way to know which configuration is active.

How Game Providers Configure RTP by Jurisdiction

This is the part that most casino review sites get wrong. They treat RTP as a fixed property of a game, like its theme or its number of reels. In reality, most major providers offer multiple RTP tiers for each title, and the operator chooses which tier to deploy.

A typical arrangement might look like this: a provider releases a slot with four available RTP settings — 97%, 96.5%, 95%, and 94%. The UKGC version almost always runs at the top or second tier, partly because UK operators know that informed players check and partly because the regulatory environment encourages transparency. An offshore operator might select the 95% or 94% tier to increase their margin, particularly if they are offering higher bonuses that need to be funded from somewhere.

The provider does not usually care which tier the operator selects. Their game is certified as fair at all available settings, and the RTP choice is a commercial decision made by the operator, not a fairness decision made by the provider. This is why the same game from the same provider can have meaningfully different RTPs at different casinos — and why “non-GamStop casinos have better RTP” is an oversimplification.

Some providers have begun publishing their available RTP tiers publicly, which helps. But the operator’s selection is not always disclosed, and at offshore casinos there is no regulator requiring them to do so.

Why Independent RTP Verification Is Harder Offshore

At a UKGC-licensed casino, every game must be tested by an approved testing house — companies like eCOGRA, iTech Labs, or GLI. These organisations verify that the random number generator produces genuinely random outcomes and that the actual RTP aligns with the stated figure. The results are audited periodically, and the operator must make RTP information available to players.

At an offshore casino, independent testing is optional. Some reputable non-GamStop operators voluntarily engage testing houses and display their certifications. Others do not. The absence of mandatory third-party verification means that an offshore operator could, theoretically, run games with RTPs lower than the provider’s published settings. The risk is low with established providers — they have contractual minimums and reputational stakes — but it is non-zero with smaller or proprietary game studios that operate exclusively in the offshore space.

For players, the practical guidance is this: if an offshore casino does not display RTP information for individual games, or if it does not list any third-party testing certification, you should assume the games are running at the lowest available RTP tier. That assumption may be wrong in some cases, but it is the only rational default when verification is absent. A casino with nothing to hide will show you the numbers.

Prepared by the StakeVault editorial staff.