Highest RTP Slots in the UK 2025

Getting to know High RTP Slots

Before exploring high RTP slots, it is essential to clarify one thing: a high RTP does not guarantee a win. RTP is a long-term average, so it cannot predict what will happen in a short session, and gambling always involves risk. If you choose to play, only use money you can afford to lose, and set a clear budget and time limit before you start. 

The highest RTP slots return the most money to players over a long period of time. Being able to recognise slot machines with the highest RTP (or Return to Player) allows gamblers to wager in a way that gives them a clear understanding of the percentage of money they are likely to lose over a long period.

Every slot machine available to play via legal online casinos in the UK will provide details on slots RTP. This is the percentage that, over the long run, the slot machine will give back to its players. Slot machines with higher slots RTP tend to return more money over the long run. 

This article explains what the RTP of slots is, how to understand it, and how it can be used to make more informed decisions when playing online slot machines.

What is RTP in slots?

Slots RTP is the percentage of money put into the machine that is returned to players over the long run, which can be millions of spins. Let’s say that a slot’s RTP is 98%. This means that over the long run, for every £100 put into the slot machine, £98 will be returned to the players.

As conveyed in our RTP Explained guide, the United Kingdom Gambling Commission, also known as the UKGC, requires that details on slots’ RTP be made public and easily visible on the machine or on the instructional page. It is essential to note that a slot’s RTP is mathematically derived, based on the internal workings of a slot machine.

The percentage is theoretical and based on play over the long run. This can be millions of spins, which are many more than an individual will play over the course of a lifetime. In the short term, due to variance and volatility, more than the theoretical RTP of a slot machine can be won or lost from any given slot machine.

RTP vs. slots volatility/variance: What is the difference?

Slots’ RTP is a mathematically derived number, based on the calibration of a slot machine’s random number generator. The random number generator is programmed to, over the long run, retain a certain percentage of the money put into the machine and to return a corresponding rate. The latter number is the slot’s RTP. However, for each spin, the outcome is entirely unpredictable and not influenced by previous results.

If a slot machine has an RTP of 96%, this means that over the long run, the machine is programmed for players to receive back £96  for every £100 wagered on the machine. As all gamblers know, however, casino games are characterised by variance and volatility.

These two factors make the games unpredictable and fun to play. Variance and volatility allow for unexpected outcomes.

To put it simply, slots RTP is equal to the long-term payout from a slot machine. It is disrupted by volatility, which, over the short run, makes the payout unpredictable. The unpredictability, statistically speaking, is variance. In the short term, payouts are controlled by volatility and variance. Volatility impacts the payout distribution. Hit frequency, which is how often the slot machine delivers a winning outcome, is not the same as return to player.

Despite all that, with all other things being equal, it makes sense to play slot machines with the highest slots RTP.

Are high RTP slot machines safe to play?

When gambling on licensed sites in the United Kingdom, all approved slot machines by the UKGC are safe to play.

However, regardless of the slot’s RTP on a machine, it is essential to remember that the percentage of money returned to gamblers comes into play only in the long term, which can span millions of spins. Over the short term, considering money won or lost, anything can happen.

Even on regulated platforms – where government-mandated rules ensure that gamblers are looked after – playing safely remains a priority. This can be accomplished by setting win/loss limits, avoiding alcohol when playing and reading game rules ahead of time. 

You can further enhance safety by setting win and loss limits for gambling. Smart players stop playing when those limits are reached, either in the positive or the negative. Always play safely to help avoid gambling problems.

UK rules that further protect UK slot players 

The UKGC has rules in place that provide clarity and protect players. The idea is to ensure that players understand how gambling devices work, that limits are in place to benefit them, and that there is no confusion about promotions for gamblers.

Here are several rules that are integral to ensuring that slot players have added protections:

Auto-play ban

The UK Gambling Commission has forbidden the use of auto-play on slot machines.

This sets the machine ahead of time for a certain number of spins. For example, let’s say you put in £100 and want the machine to do 20 spins at £5 each, it could do that without stopping. However, the UKGC has determined that the autoplay feature can lead some players to lose track of their actions and potentially gamble on two different games simultaneously.

Now, with that no longer allowed, you have a better chance of deciding whether you want to continue and to think about your gambling. It’s a safety feature that will enable you to stop playing at any time.

Reduced slot-spin speeds

Since online slot machines are digital, with the outcomes determined by the results of random number generators, wagers can be resolved in split seconds.

The UKGC has deemed that each spin must last for at least 2.5 seconds. This is done to slow down the action and give players time to watch the spin and consider wagering on another one.

Reduced stake limits

As of April 9, 2025, stake limits for slot machine players have been introduced. Adults aged 25 and older can bet no more than £5 per spin. Those between the ages of 18 and 24 are capped at £2 per spin. This is being done to limit gambling-related harm.

Improved promotions

According to the UKGC, new regulations impose specific controls on bonuses and promotions for slot machines, as well as for other forms of online gambling. One adjustment is what’s known as the 10x cap.

This means that to receive a bonus, typically based on the amount deposited to a site, the maximum bet required to claim that bonus is usually 10 times the deposited amount. In other words, if you are eligible for a £100 bonus, based on a deposit of £100, you can be required to put through £1,000 of wagers, but no more.

There is also a promotions-bonus rule, which is designed to create clarity for players and put a stop to so-called “cross-product promotions.”

In the past, sites were allowed to offer players a promotional bonus by making them gamble across multiple products – such as a casino, sports betting, and horse racing. Now, they can be required to bet on only one product to receive the promotion.

How to Choose the Best RTP Slots in the UK

CasinoHawks works hard to make sure players understand the various slot machines in terms of how they play, the bonuses they offer, the slot’s RTP that can be expected in the long run and everything else you need to know to have a fun, transparent experience.

Here are some tips to make sure that you understand our slot machines

 ✔ Read our slot reviews: Before playing a slot machine, read our slot reviews to learn about the machines and all of their features. These include slots RTP (money that gets returned to the player in the long run), volatility (the game’s level of unpredictability), the machine’s features and the risks/rewards they present, the maximum win percentage (for example, Mega Joker offers as much as 2,000x your bet), the machine’s provider and the name of the lab that tested it.

 ✔ Understand RTP: RTP stands for Return to Player. This is the amount of money that, over the long term, a slot machine is designed to give back to players. Let’s say the machine has a slots RTP of 97%. This means that for every £100 put into the slot machine, £97, over the long run will be returned to players.

 ✔ Check the configured RTP version: Many games offer multiple RTPs. The percentage returned to the player can vary depending on the denominations played. In some instances, higher denominations result in higher RTP. That said, it is inadvisable to bet more than you are comfortable betting to get the higher RTP.

 ✔ Bonuses don’t increase a slot machine’s RTP: Casinos sometimes offer bonus incentives to customers. This means, for example, that if you deposit £100, you may receive a £100 bonus added to your account. It can require that you play through the £100 as many as 10 times, but no more than that. Playing for a casino bonus will not impact the RTP.

 ✔ Consider bet sizes and the UK stake limits: As of April 9, 2025, stake limits for slot machine players have been introduced. Adults aged 25 and older can bet no more than £5 per spin. Those between the ages of 18 and 24 are capped at £2 per spin. This is being done to limit gambling-related harm.

 ✔ Consider volatility/variance: While it is essential to know the slots’ RTP offered on a machine, it is also important to remember that the slot’s RTP plays out over the long run, which can total millions of spins. In the short term, the RTP of slots is influenced by volatility and variance. Those two terms refer to the unpredictability of slot machine outcomes and the extent to which wins and losses can accumulate. High RTP does not necessarily equate to low volatility. In fact, a high slots RTP game can also have high volatility. Such is the case with the slot machine called Book of 99. 

 ✔ Read our casino reviews: Our casino reviews can serve as a guide. They contain information on casinos that we have carefully scrutinised. Those casinos have been licensed by the UKGC. These sites are tested by outside labs such as eCOGRA, which describes itself as a gaming and certification specialist, and GLI, which provides testing for the gaming industry.

 ✔ Set a budget and play safely: Before sitting down to play an online slot machine, be sure to have a clear budget in mind, specifying both your desired win and acceptable loss. Once those points are reached, it is best to end your session and use your time for something else.

The critical takeaway here is that gambling should be made as safe as possible for those who enjoy it.

Where to play the best high RTP slots in the UK

Here is a sampling of sites where you can find the best high-RTP slots in the UK. While Return to Player will only be resolved in the long run, for the short run, which is what we all play, these sites promise to be fun, regulated, and loaded with variety.

Bet365

Bet365 is a strong option for high RTP slots because bigger, established operators typically offer a breadth of titles and a stable user experience, making it easier to compare slots and check information consistently. The best way to use Bet365 for RTP focused play is simple: pick a slot, open the help panel, confirm the RTP and then decide whether it fits your style. Keep play controlled by using account tools, such as limits and session management.

Megariches

Megariches can work well for finding high RTP slots, as it offers a slots-heavy catalogue with popular providers and straightforward game navigation. The practical advantage is speed  you want to be able to search, filter and open a game’s info section quickly to verify RTP and key rule such us volatility, bonus features and any caps. As always, confirm you are on the UK-licensed site and treat RTP as information for making more informed choices, rather than as a way to beat the game. 

Playzee

Playzee can be a good choice for high RTP slots if you use it as a library first, browsing the slot range, opening the game info screen, and confirming the RTP before playing. The key benefit to look for is variety; a more expansive slot catalogue gives you more chances to find titles with higher RTP settings. 

Progressive Jackpots and RTP

When playing games with jackpots, clarity is often maintained by displaying the RTPs for separate slots, both for the base game and for the jackpot.

It is important to note that since money for the jackpot comes out of money wagered on the game, a jackpot can reduce a slot’s RTP.

To ensure that progressive jackpot systems operate fairly, the UKGC deems that jackpot rules, including how it is funded, must be clearly displayed for players to see.

Additionally, the UKGC mandates that theoretical slots RTP be displayed in player-facing rules.

Mastering high RTP for online slots: Your path to smarter spins

Here are some tips that can help you when playing slot machines and aiming to stay within your gambling budget:

• Maintain bankroll management by setting clear win and loss limits before playing the game.
• Take breaks from playing so that you can step away from the game and have time to think about how things are going.
• Avoid the gambler’s fallacy, which is the belief that a random event in the future is dictated by events in the past. Every spin of the slot machine is independent of every spin that preceded it.
• Keep gambling as a fun activity. When it ceases being fun, that is the time to stop and reconsider.

Frequently asked questions

What is the highest RTP slot game in 2025?

Currently, Ugga Bugga has the highest RTP around, sitting at 99.07%. Other games with above-average RTPs include Mega Joker, Book of 99, Jackpot 6000 and Starburst.

How to find a high RTP online slot game?

To find a high RTP slot machine, check the game’s information section. Gaming providers must provide clear and accurate details of their game to ensure transparency for players. This includes RTP rates and slot variance.

Are High RTP slots free to play?

Some casino sites offer free-to-play demo games for high RTP slots. However, to play these games for real money, you must sign up with a casino and make a monetary deposit.

What slot game has 99% RTP?

Few high RTP UK slots have over a 99% rate. Ugga Bugga, Book of 99 and Mega Joker are some of the few slots with over 99% RTP. But providers release new games frequently, so keep an eye out for the latest high RTP slots UK.

Author

Michael Kaplan

Senior Casino Games Expert

Michael Kaplan is an award-winning journalist, author, and gambling expert whose career spans over three decades, covering the world of casinos, poker, and high-stakes play. Michael Kaplan is the author of five books. His books include “Aces and Kings: Inside Stories” and “Million Dollar Strategies from Poker's Greatest Players” and, published this past May, “Advantage Players: Inside the Winning World of Casino Virtuosos, Master Strategists, and Mathematical Wizards”. Michael’s magazine article, 'Baccarat Machine,' is presently being adapted into a scripted feature film.