Every slot page on a UK casino site lists an RTP figure. Most players notice it vaguely and move on. That is a shame, because once you understand what the number actually represents, it becomes one of the most useful tools you have for getting the most out of any bonus offer.
This guide covers the definition, the calculation, the important caveats about what the number does and doesn't guarantee, and then the part that most RTP guides leave out entirely: how RTP feeds into expected value and how to use it when choosing which games to play on your offers. There is no gatekeeping behind jargon here. If you have never heard of RTP before today, start from the top. If you already know the basics, jump ahead to the section on offers.
What is RTP?
RTP (Return to Player) is the percentage of all money wagered on a casino game that the game is designed to pay back to players over a very large number of rounds. A slot with 96% RTP will, across millions of spins, return £96 for every £100 wagered. A 97% RTP slot returns £97. The remaining percentage is the house edge.
RTP applies to every casino game, not just slots. Table games have RTP figures too: European roulette sits around 97.3%, blackjack with basic strategy can reach 99.5%, and so on. When we talk about spins in relation to RTP, we're specifically referring to slot spins. The same underlying principle applies across all game types, but the way the maths plays out varies by game.
The house edge is simply 100 minus the RTP. On a 96% RTP slot, the house keeps 4% of all money wagered on average. On a 96% RTP slot and a 97% RTP slot, the difference in house edge is 1 percentage point. That sounds small, but across the volume of wagering involved in a typical bonus offer, it adds up to a real and quantifiable difference in what you expect to keep.
One thing to be clear on from the start: RTP is calculated on money wagered, not money deposited. If you deposit £10 and wager it on a slot, then wager your winnings again, and keep wagering, the RTP applies to every individual wager. The total amount wagered quickly exceeds your original deposit. This distinction matters a lot when you are calculating the expected cost of a wagering requirement on a bonus.
How is RTP calculated?
Example: A slot pays out £950,000 across £1,000,000 of total slot wagers. RTP = 950,000 / 1,000,000 × 100 = 95%.
The figure you see published for any slot is not calculated from live player data. It is a theoretical figure, worked out by the game developer across hundreds of millions of simulated spins before the game ever goes live. The maths accounts for every possible combination the game's random number generator can produce, weighted by how frequently each combination occurs.
Before a slot can be released to players in the UK, that theoretical RTP must be verified by an independent testing laboratory. The main ones you will see referenced are eCOGRA and BMM Testlabs. Their job is to confirm the game's actual mathematical behaviour matches what the developer says it is.
The UK Gambling Commission requires all licensed operators to display RTP information to players. You can find it inside every slot in your casino's game library, usually by clicking the information icon (often labelled i, ?, or accessible through a help menu). The exact figure varies slightly by provider and by casino. More on that in the section on finding RTP below.
The published RTP is a theoretical long-run average, not a live measurement from real player data. The actual RTP recorded across all real sessions at a casino will tend to converge toward the theoretical figure over millions of spins, but no individual session, or even a full day's play, is guaranteed to land anywhere near it.
Why RTP is a long-run average, not a session guarantee
This is the part that most RTP guides mention briefly and then gloss over. It deserves more than a sentence.
A 96% RTP slot does not return £96 every time you wager £100. It returns something close to £96 per £100 wagered across tens of millions of spins combined. In any individual session, the actual return could be anything from £0 to several times your stake. The maths only becomes reliable at a scale no individual player ever reaches in a single sitting.
Think of it like a coin flip. Flip a fair coin 10 times and you might get 8 heads. Flip it 10,000 times and you will be very close to 50% each way. The underlying probability does not change, but the short-run result can deviate wildly from the long-run average. Slots work the same way. RTP tells you about the coin, not about your next 50 flips.
What this means in practice: RTP is a useful planning tool for calculating expected value across many offers. It is not a prediction for any individual session. Some sessions will beat the expected return. Some will fall well short. That spread of outcomes is called variance, and it is shaped largely by the slot's volatility, which is a separate number from RTP. The slot volatility guide covers how the two interact.
RTP and volatility: two different questions
RTP answers "how much does this game pay back overall?" Volatility answers "how does it distribute those payouts?" Two slots can have almost identical RTPs and feel completely different to play, because one drips out small wins steadily while the other goes quiet for long stretches and then lands big.
God of Storms and Big Bass Splash are a good example. God of Storms has an RTP of 96.14% and low volatility: it pays back in a relatively even spread of small wins. Big Bass Splash has an RTP of 96.71% and high volatility: longer dry stretches, but the bonus feature when it lands is substantial. Both RTPs are broadly similar. The experience across 50 spins is quite different.
For bonus wagering purposes, both numbers matter. RTP tells you the expected cost of qualifying wager and the expected return on free spins. Volatility tells you how widely the actual result of your session might deviate from that expected value. If you want the full picture on how to use both when choosing a slot, the volatility guide goes through it in detail.
What RTP means for your offers
This is where the RTP figure stops being background knowledge and starts earning its place. The expected value on any casino offer depends on a small number of inputs, and RTP is one of them.
The number that actually matters when you are deciding whether an offer is worth doing is EV, expected value. RTP is a key input to that calculation, but it is not the whole picture. A slot can have excellent RTP and still be the wrong choice for a particular offer. Understanding both the role RTP plays and its limits is how you get to the right answer consistently.
Choosing your qualifying slot
Many welcome offers have a qualifying wager step: deposit and spend a certain amount on slots before the bonus or free spins are credited. The RTP of the slot you choose for that qualifying wager directly determines the expected cost of getting through it.
Say you need to wager £10 on slots to unlock your free spins. On a slot with 97.87% RTP (Starmania, made by NextGen Gaming, a solid first-choice for qualifying wagers), you expect to get back £9.79 of that £10 on average. The expected cost of the qualifying step is around 21p. On a slot with 94% RTP, the same £10 wager has an expected cost of 60p. Neither number is alarming on its own, but if you run 30 similar offers over the year, the difference in qualifying slot choice compounds to roughly £11.70 in additional expected losses, simply from not picking the right game each time.
The qualifying step is a cost you accept in order to unlock the value sitting in the bonus or free spins. The goal is to make that cost as small as possible. Picking a high-RTP slot is the simplest way to do that, and it costs you nothing extra.
Working out what free spins are actually worth
Example: 50 spins at £0.10 per spin on a 97% RTP slot = 50 × £0.10 × 0.97 = £4.85 expected value.
RTP is one of only three variables in that formula. The number of spins and the spin value are set by the offer terms. The RTP of the slot is where you have a choice, and it is the only variable in the formula you can influence.
On an offer with 50 free spins at 10p, the difference between a 97% RTP slot and a 94% RTP slot is 15p in expected return. That is modest on a single offer. Across a year of running offers, the habit of always choosing the highest eligible RTP makes a real difference to total returns. The EV calculator lets you run these numbers for any specific offer before you start.
Why high RTP alone doesn't tell you if an offer is worth doing
This is the part that most casino sites never explain, because their audience is not trying to extract value from offers.
RTP tells you how much a slot returns per pound wagered. It does not tell you whether an offer's total expected value is positive. For that, you need to weigh the bonus value against the expected cost of any wagering requirement attached to it. A slot's RTP being high does not automatically make an offer good value if the wagering requirement is large enough to eat through the bonus and then some.
A straightforward example: Offer A gives you 50 free spins at 10p with no wagering on winnings. Offer B gives you 50 free spins at 10p with 35x wagering on whatever you win. Both offers use a 97% RTP slot. Offer A: expected return is £4.85, fully withdrawable. On Offer B, the spins still return £4.85 in expectation, but then you need to wager that amount 35 times. The expected cost of wagering £4.85 at 35x on a 97% RTP slot is around £5.08 in losses. The offer's net expected value is negative. The slot's RTP was exactly the same in both cases.
There is also the progressive jackpot trap. Some slots advertise an RTP of 96% or higher, but that headline figure includes the jackpot contribution, which might account for 2-3% of the total RTP. The realistic non-jackpot RTP, the part that actually comes back to you in regular play, is meaningfully lower. For wagering purposes, the effective RTP is what matters, not the headline figure.
The short version: use RTP to choose your qualifying slot and to estimate free spin value. Use the full EV calculation to decide whether an offer is worth running at all. The understanding expected value guide covers the full calculation, and the EV calculator does the maths for you.
High-RTP slots worth knowing about
These are slots referenced across this site's offer pages, chosen for their verified RTP figures and their availability at multiple UK-licensed casinos. Always confirm the RTP inside the active game at your specific casino before playing, as some providers allow operators to run lower-RTP variants.
These are split by context. The Tombola slots are only available at Tombola and its sister sites. The NetEnt group are available more broadly but require an in-game RTP check, as NetEnt permits operators to run lower-RTP variants of the same slot.
Tombola (casino-specific, consistently high RTP)
| Slot | RTP | Notes |
|---|---|---|
| Carnival | 98.00% | Tombola exclusive. One of the highest RTPs available anywhere. |
| The Deep | 98.00% | Tombola exclusive. Matches Carnival for top RTP. |
| Olympus | 97.02% | Tombola exclusive. |
| Pharaoh | 96.99% | Tombola exclusive. |
| Jungle Spins | 96.98% | Tombola exclusive. |
General availability (check RTP in-game at your specific casino)
| Slot | Provider | RTP | Volatility | Notes |
|---|---|---|---|---|
| Starmania | NextGen Gaming | 97.87% | Low-medium | First-choice qualifying slot across many offers. RTP is consistent across operators. |
| Golden | NetEnt | 97.22% | Low-medium | Check in-game. NetEnt permits casino-specific RTP variants. |
| Jack Hammer 2 | NetEnt | 97.07% | Low | Check in-game. Low variance makes results predictable. |
| Secrets of Atlantis | NetEnt | 97.07% | Medium | Check in-game. NetEnt permits casino-specific RTP variants. |
| Wrath of the Deep | Blueprint Gaming | 97.04% | Medium | Eligible for free spins at specific operators including Bet365. |
| Wild Wild West: The Great Train Heist | NetEnt | 96.74% | Low | Low variance. Good option where higher-RTP NetEnt slots are unavailable. Check in-game. |
| Big Bass Splash | Pragmatic Play | 96.71% | High | Strong RTP but high volatility. Frequently included in free spin offers across Pragmatic casinos. |
| Finn and the Swirly Spin | NetEnt | 96.62% | Low | Low variance. Check in-game. NetEnt permits casino-specific RTP variants. |
| God of Storms | Play'n GO | 96.14% | Low | Reliable qualifying slot where higher-RTP options are not available. Results stay predictable. |
NetEnt, Pragmatic Play, and Red Tiger all permit operators to run reduced-RTP versions of their slots. The same slot can show a different RTP at different casinos. Never assume the RTP from another source is accurate. Load the game, open the rules or info panel, and read the figure shown there.
How to find the RTP of any casino game
UK regulations require all licensed casinos to display RTP information to players. For slots, it is shown inside the game itself. Here is where to look by provider:
NetEnt slots: Click the ? button inside the game, then look for "Return to Player" in the game information panel.
Pragmatic Play slots: Tap the i symbol in the corner of the game window, then navigate to the rules or info tab.
Red Tiger slots: Open the Help or Rules menu from inside the game.
Play'n GO slots: Open the Rules panel via the menu icon inside the game. The RTP is listed alongside game rules.
Blueprint Gaming slots: Click the i icon or open the Paytable section; RTP is listed at the bottom of the game rules.
The most important caveat: the RTP you see on a casino's promotional page or a third-party review site may not match what the game is actually running at that specific casino. NetEnt, Pragmatic Play, and Red Tiger all allow operators to configure their slots to run at lower RTPs than the base game. The only figure you can trust is the one shown inside the game at the casino you are actually playing at.
If you are checking RTP before deciding which slot to use for a qualifying wager, the correct process is: load the game at your casino, open the info panel, read the figure, then close the game and either play it or choose a different one.
FAQ
What does RTP mean in casino?
RTP stands for Return to Player. It is the percentage of all money wagered on a casino game that the game is designed to return to players over a very large number of rounds. A 96% RTP slot returns £96 for every £100 wagered across millions of spins on average. This is a theoretical long-run figure: individual sessions can and will deviate significantly from it.
Does RTP change between casinos?
Yes, for some providers. NetEnt, Pragmatic Play, and Red Tiger all allow individual operators to configure their slots at a lower RTP than the base game. A slot that runs at 96.09% at one casino might run lower elsewhere. This is why you should always check the RTP inside the active game at the specific casino you are playing, rather than relying on figures from another source.
Is RTP the same as the house edge?
They are two sides of the same number. If a slot's RTP is 96%, the house edge is 4%. The house edge is the percentage the operator keeps on average across all wagers. They always add up to 100%. RTP tends to be how games are marketed to players; house edge is more commonly used in academic and industry contexts.
Does stake size affect RTP?
For most slots, no. The theoretical RTP applies regardless of how much you wager per spin. The main exception is progressive jackpot slots, where eligibility for the jackpot pool sometimes requires a minimum stake per spin. Below that threshold, you are contributing to the jackpot pool without being eligible to win it, which effectively lowers your RTP on the regular game. The stake size strategy guide covers this in more detail.
Is high RTP enough to make an offer worth doing?
No. RTP is one input to the expected value calculation, not the whole picture. A high-RTP slot reduces the expected cost of a qualifying wager and increases the expected return on free spins, but the offer's overall expected value also depends on the wagering requirement, the size of the bonus, and the number of spins. Use the EV calculator to assess the full offer, and the offer simulator to model how variance might affect your actual result.
RTP is one input to expected value. It tells you what a slot costs per pound wagered. Expected value tells you whether the whole offer is worth running.
Every offer on this site already has the qualifying slot and its RTP noted, so you do not need to research it from scratch each time. The EV on each offer is calculated using those figures. What this guide gives you is the context to understand the number, apply it yourself if you need to, and recognise when a high-RTP slot alone is not the whole answer.