Casino Games Guide: RTP, House Edge, and What the Numbers Actually Mean

Two numbers determine the long-term relationship between you and any casino game: RTP and house edge. They describe the same thing from opposite directions. Understanding them does not eliminate variance; you can still win or lose significantly in any session, but it does allow you to compare games objectively and make informed decisions about where to play.

This guide covers how these figures work across different game categories, which providers publish verified data, and what to look for when the numbers are not easy to find.

RTP: What Return to Player Actually Means

RTP (Return to Player) is the percentage of all stakes a game returns to players over a statistically significant number of rounds, typically millions of simulated spins or hands. A slot with 96% RTP returns £96 for every £100 wagered in aggregate. The remaining £4 is the house edge.

The critical word is aggregate. RTP is not a session guarantee. In a single session of 200 spins, variance determines outcome far more than the theoretical return percentage. RTP only becomes predictive over millions of rounds, relevant at the scale a casino operates, not at the scale of an individual player.

What RTP is useful for: comparing games against each other. A 97% RTP slot loses half as much per pound staked as a 94% RTP slot over time. Over many sessions, this compounds into a meaningful difference.

Some casinos operate adjusted RTP versions of popular titles, typically 1–3% lower than the default, which is disclosed in the game information panel. Check the in-game RTP if it matters to you; the default figure published by the provider may not be what the casino is running.

Volatility: The Number That Changes Your Session

Volatility (also called variance) describes how results are distributed. High-volatility games pay infrequently but in large amounts. Low-volatility games pay more often in smaller amounts. Two games can have identical RTPs and completely different volatility profiles.

• Low volatility: frequent small wins, gradual bankroll movement. Examples: Starburst, Aloha Cluster Pays. Suitable for longer sessions on a fixed budget.
• Medium volatility: balanced frequency and size of wins. Most mainstream slots fall here. Examples: Book of Dead, Gonzo's Quest.
• High volatility: infrequent wins, larger payouts. Long losing runs between significant wins. Examples: Dead or Alive 2, Legacy of Dead.
• Very high volatility: extended dead spins punctuated by potentially large multiplier wins. Associated with providers like Nolimit City and Hacksaw Gaming. Examples: Tombstone RIP, Mental, Wanted Dead or a Wild.

Very high volatility games are popular precisely because the maximum win potential is large, but the average session outcome is also the most likely to drain a bankroll before the feature triggers. They are not suited to bonus wagering with a limited time window.

Online Slots

Slots account for the majority of a typical online casino's game library. The core mechanics have evolved significantly from the three-reel formats.

Paylines and ways to win: Classic slots use fixed paylines, typically 9, 25, or 50. Ways-to-win slots (243, 1,024, or more) pay for matching symbols in adjacent reels regardless of position, increasing hit frequency at the cost of potential prize size per combination.

Megaways: A mechanic licensed by Big Time Gaming (BTG) where each reel contains a random number of rows on every spin, generating up to 117,649 ways to win. Used by many providers under licence, including NetEnt, Pragmatic Play, and Blueprint Gaming. Megaways slots tend toward high volatility due to the variability of the multiplier potential in cascading win features.

Bonus Buy (Feature Buy): Available in jurisdictions where permitted, this allows you to purchase direct access to the bonus round at a fixed cost, typically 50–100× the base bet. The purchased feature has the same expected value as triggering it naturally, but eliminates base game variance. Not available in the UK (prohibited by the UKGC) or in some other regulated markets.

Providers to know: NetEnt and Microgaming built the industry; Pragmatic Play is currently the largest by volume; Play'n GO is dominant in Northern Europe; Nolimit City, Push Gaming, and Hacksaw Gaming produce higher-volatility content for experienced players; Evolution owns NetEnt and supplies most live casino infrastructure globally.

Table Games and House Edge

Table games have a fixed, calculable house edge based on the rules of the game and, in skill-based games, the strategy employed. Unlike slots, optimal strategy in blackjack or video poker genuinely reduces the house edge to its mathematical minimum.

American roulette's additional double-zero pocket nearly doubles the house edge over the European single-zero version. When both are available, there is no mechanical reason to choose the American variant. The baccarat tie bet, often placed by recreational players for its higher payout (8:1 or 9:1), carries a house edge fourteen times higher than the banker bet. It is one of the least favourable bets in the casino.

Live Casino

Live casino games are real table games streamed from purpose-built studios, operated by trained dealers and broadcast in real time. The RTP and house edge figures are identical to their digital equivalents; the rules do not change. The difference is the experience: a live blackjack table operates at a slower pace, with visible card handling and the ability to interact with the dealer.

Evolution is the dominant live casino provider, operating studios in Latvia, Malta, and several other locations. They supply the majority of live tables at major online casinos and also produce game show-style live titles (Crazy Time, Monopoly Live, Dream Catcher). These game shows carry higher house edges than standard table games, typically 3–10%, but are designed for entertainment rather than optimal return.

Pragmatic Play Live and Playtech Live are the main alternatives, used at a number of operators that prefer not to be entirely dependent on Evolution infrastructure.

Live tables typically have minimum bets higher than their digital equivalents: £1–£5 is common for standard blackjack, higher for VIP tables. Low-stake live options exist but are more limited than the digital game selection.

Progressive Jackpots

Progressive jackpot slots pool a percentage of every stake across all players into a jackpot that grows until one player triggers the win condition. The most prominent network jackpots, including Mega Moolah (Microgaming) and Age of the Gods (Playtech), have paid out sums in the tens of millions.

The trade-off: the RTP figure published for progressive slots includes the jackpot contribution. When the jackpot has not been won recently and is below its expected average, the base game RTP is lower than the headline figure. In practical terms, progressive jackpot slots deliver lower average base game returns per spin than comparable fixed-payout slots. You are trading regular return percentage for jackpot exposure.

Some casinos exclude progressive jackpot slots from bonus wagering or cap winnings from bonus play at a fixed amount (e.g., £1,000 from bonus funds regardless of the jackpot size). Always check this before playing jackpot titles while a bonus is active.

How RNG Works and Who Certifies It

Online casino games use a Random Number Generator (RNG), a cryptographic algorithm that produces unpredictable outcomes on every spin or hand. A correctly implemented RNG means no pattern, no predictable sequence, and no influence from previous results.

Regulated operators are required to have their RNG independently certified. The main testing laboratories are:

• eCOGRA, a UK-accredited testing facility that audits both RNG implementations and published RTP figures. The eCOGRA seal on a casino indicates regular third-party auditing.
• GLI (Gaming Laboratories International), one of the largest independent testing labs globally, operating across multiple regulated markets.
• iTech Labs, an ISO-accredited Australian lab widely used by European-market providers.
• BMM Testlabs, established in the land-based casino sector, now widely used for online game certification.

If a casino displays the logo of one of these labs and links to a current certificate, the RNG has been independently verified. If no third-party certification is visible and the casino holds only a Curaçao licence, the published RTP figures should be treated with caution; there is no external verification obligation under that jurisdiction.

How to Check a Game's RTP

Most games include an information panel (the “i” button or paytable icon) that states the RTP. For slots, this is usually listed as a percentage. Some casinos also publish a full game RTP list in their responsible gambling or game fairness section.

If you cannot find the RTP in-game, search the provider's website for the game name; most established studios (NetEnt, Play'n GO, Pragmatic Play, Push Gaming, Nolimit City) publish RTP figures in their game sheets or press kits. If neither source provides a figure, that is itself relevant information.