Top 10 UK Online Slots Casinos (2021)

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The Best Online Slots (2021) - Real Money Slot Games

Slots gambling machines have been around for decades, but they have come a long way since the days of so-called one-armed bandits. Today’s online slots are made with sophisticated software and graphics to provide a fun and exciting gaming experience.

In fact, over 70% of online casino games are slots that are available on online gambling sites or mobile casino apps.

The chance to win life-changing amounts of money from small stakes on a single spin of the reels makes them very appealing, while a lot of them are fun to play in their own right.

Thousands of different online slots are available to play these days, with various different providers developing games that are featured on the top online slots sites in the UK.

So much choice can be overwhelming for some customers, which is why we have put together the ultimate guide to the best online slot sites in the UK.

You can simply compare all the best online casinos that offer real money slots in our list above. Or check out our detailed comparisons below as we compare the number of online slots available on each casino, the average payout, and which top game providers are being used such as NetEnt and Microgaming.

Why Are Online Slots So Popular?

The popularity of online slots in the UK lies in the fact that they are pretty easy to play, compared to more complicated casino table games like roulette and blackjack that have fairly complex sets of rules and strategies that need to be learnt and followed.

Another big factor in the success of online slots is the fact that you can win big prizes - and we mean seriously BIG prizes! Some of the progressive jackpot online slots have prizes that run into millions of pounds.

Finally, many online casinos offer free spins as an incentive to play on their site. This means that you get a set amount of free bets on the online slots game and win bonus money. The qualifying wagering requirements for these free spins varies from casino to casino, so you need to check the terms and conditions on their website.

So, online slots are great fun to play, easy to learn and give you the chance to win some serious cash. Now you just need to know how to play them, which ones are the best, and where to go to find them.

Convenience

As mentioned earlier, online slots are very easy to learn and simple to use. You can learn how to play them in a matter of minutes, whereas roulette may take up to an hour to learn the rules and even longer to learn the best betting strategies. The simplicity of online slots makes them very attractive for recreational gamblers.

You can even select to auto-spin or autoplay, which means you don’t even really need to concentrate on what is going on until the software needs your input. The fact that you can easily play online slots on a mobile app makes them even more convenient - you can literally play them anywhere.

Big Jackpots

The standard jackpots on online slots are typically bigger than those in land-based casinos or clubs. The size of the standard jackpot depends on the value of the stakes being played, the slots game, and the online casino.

Pretty much all online casinos offer slots that are connected to a progressive jackpot. A progressive jackpot is a system that takes a tiny percentage from each spin on connected slots machines and adds it to the grand prize or the jackpot. The jackpot is won either at random - by spinning in the correct symbols - or by unlocking and winning a special feature or bonus game.

Most progressive jackpots are £10,000’s or £100,000’s in value, with some of the jackpots at bigger sites running into £millions!

High Payout Percentages (Return to Player Rate) 

Most online slots have an RTP rate of between 94% and 97%. What this means is that you get between 94 and 97% of your bets returned to you. For instance, take a slots game with an RTP of 96%, if you play over a large sample, let’s say 100,000 spins, you’ll get an average of 96p back for every £1 you spend. The remaining 4p from each £1 goes to the online casino to make up their profit. 

Slots Tournaments

Slots tournaments are promotions run by some online casinos in which players compete against each other for a prize pool. The rules vary from site to site, but usually, there is a leaderboard of winnings during the set time period of the tournament and the players that rack up the most winnings will get extra prizes. There is usually a grand prize for the overall winner which can be pretty high depending on the popularity of the site and the tournament being played.

What Are Online Slots?

Online slots are based on the mechanical slot machines of old, which were sometimes known as one-armed bandits or fruit machines). However, modern online slots don’t have any mechanical spinning reels, instead, they simulate the spinning of reels.

Players are awarded prizes if they get matching symbols across the reels. Depending on the slots game being played, prizes may be awarded for matching lines that go in different directions across the reels. On most online slots games, you can select how many lines to play, paying a larger stake per spin for more lines. 

Some symbols pay bigger prizes than others, but these are programmed to be less statistically likely to come in. The jackpot symbols are the least likely to spin in, but they have the biggest cash prize award.

Most online slots games also have a feature that is triggered by matching certain symbols. The feature may be a sub-game that involves completing certain challenges, puzzles or games.

When you win cash prizes on an online slots game, your balance is credited with the corresponding amount. You can then choose to either keep gambling with your winnings or cash out which moves your winnings to your casino cashier account where you can withdraw it if you want.

How Do Online Slots Work?

Online slots work in a similar way to the latest modern slots machines in casinos - in other words, there are no moving parts and everything is controlled by computer software and displayed on a screen. In the case of online slots, the software is run on a server by the casino site and displayed on your desktop computer or mobile device.

To decide the placement of the reels when they finish spinning, a random number generator (RNG) is built into the software. To ensure that the RNG is fair and based on random chance, casino sites must allow the software to be checked and audited by third-party independent inspection companies.

In the UK, online casinos must get Independent RNG Certification to qualify for UKGC licensing to operate legally in the UK. The certification inspection also makes sure that the software cannot be accessed or tampered with by players or the online casino employees.

The actual gameplay of online slots varies from game to game, but in general, you can select the stakes you want to play, the amount of cash you want to wager on each pay line, and the number of paylines you want to play. All of this combines to create a total bet for each spin.

For example, let’s say you are betting 10p per pay line with 10 paylines selected, this means that each spin will remove £1.00 from your balance. Most slots games give you the option to hit the spin button each time or use an “autoplay” feature which will continue spinning until you disable it or enter a game feature that needs your input.

After each spin, the software checks to see if there are any symbols aligned correctly along with your paylines for a payout. If so, the amount won will be automatically added to your balance.

Top 5 Slots Games in the UK (Highest Payout Percentage)

Return to Player (RTP) means the same thing as payout percentage and corresponds to the amount of money that you get back when you make a bet on a slots spin. For example, a 97% RTP means you’ll get 97p back for every £1.00 spent.

Here is a list of the top 5 slots games that have the highest payout percentage (RTP) and where you can find them.

1. Ugga Bugga (RTP = 99.07%)

Ugga Bugga is a jungle-themed slots game that has a very high payout percentage and is one of the only games out there that exceeds 99%. It’s an exciting game with 10 rows, each with 3 reels built-in, in two distinct groups. There are 10 paylines to choose from every time you spin. It is made by Playtech and is available at many UK casinos including Mansion Casino, Ladbrokes, Betfair, and William Hill.

2. Mega Joker (RTP = 99%)

Mega Joker is a popular classic style slots game and a progressive jackpot. Made by NetEnt, it’s a simple slots game to play with just 3 reels and 5 paylines, across 3 rows. The progressive jackpot makes it a popular game with casino aficionados. You can play Mega Joker at Unibet, Admiral Casino, and others.

3. Ooh Aah Dracula   (RTP = 99%)

Made by Barcrest, this is a fun themed slots game that has plenty of cool video and audio effects. It has 5 reels and 3 rows with 10 paylines. You can get free spin bonuses within the game. It is available to play at Party Casino and NetBet Casino.

4. 1429 Uncharted Seas (RTP = 98.6%)

The concept of this slot game made by Thunderkick is that the reels are part of an old sea-faring map. The visuals are great and it has a whopping 25 win lines to bet on. There are plenty of other fun features including free spin bonuses and expanding wild symbols. You can play 1429 Uncharted Seas at Dream Vegas and Pokerstars Casino.

5. Rainbow Riches (RTP = approx. 98%)

The RTP of Rainbow Riches does vary slightly from site to site, but it’s usually around the 98% mark - check the individual site’s terms and conditions or help files to find out the exact percentage. It’s a colourful and fun slots game with plenty of bonus features to enjoy. It is made by Barcrest or Gamesys, depending on the version being offered. You can find Rainbow Riches at Paddy Power, Sky Vegas, Rainbow Riches Casino, amongst others.

Top 5 Slots Sites in the UK (Highest Payout Percentage)

Here are the top 5 slots sites in the UK, from the highest average payout percentages (RTP) to the lowest.

1. Rainbow Riches Casino (Average RTP of 98.4%)

As you might expect from a site based around one of our top 5 RTP slots, Rainbow Riches Casino offers great value for money when it comes to playing slots. They have hundreds of slots games available and the average RTP is 98.4%, the highest of any other slots sites in the UK. They also have table games, live dealer games, and bingo on offer.

2. 888 Casino (Average RTP of 98.1%)

888 Casino isn’t too far behind in the number two position with 98.1% and they also have one of the widest range of slots and casino games available online too. Not to mention their excellent mobile app, regular promotions, and very generous no-deposit £88 welcome bonus. What are you waiting for??

3. Virgin Casino (Average RTP of 97.8%)

Virgin Casino leads the way in terms of customer support and visually attractive casino games, especially slots. So, you get good value for money, top-tier service, and hours of fun and excitement. Sounds good to us!

4. Monopoly Casino (Average RTP of 97.5%)

The payout percentage at Monopoly Casino is 97.5%, which is pretty good and above the industry average. They also have some of the biggest progressive jackpots available online, so don’t miss out!

5. Casimba (Average RTP of 97.3%)

With a special focus on slots, Casimba is a relatively new online casino site but has already made a good name for itself as a place to get good value for money. With progressive jackpots and other promotions running regularly, if you’re lucky you can end up with a good payday at Casimba Casino.

Different Types of Online Slots

Part of the fun of playing online slots is the wide variety of games that are available. In general, there are five different categories of online slots.

1. Branded Slots

It’s fair to say that branded slots have become the most popular type of slots games in recent years and are widely available at many online casinos.

But what do we mean by branded slots? Branded slots are games that are based on popular movies, TV shows, board games, singers, rock bands, sports teams, celebrities, etc. They are produced under license by companies such as NetEnt, Playtech, and Microgaming. In the UK, some popular branded slots are Deal or No Deal, Monopoly, I’m a Celebrity Get Me Out of Here, Game of Thrones, plus many more.

The top online casinos for branded slots are Pokerstars Casino, LeoVegas, 21.co.uk, and 32Red, both of which have dozens of different brands on offer.

2. Video Slots

Video slots are slots games that generally have five or more reels and they are combined with video and audio special effects to add to the experience. Video slots often boast some of the best features and bonuses, such as prize games. It’s fair to say that pretty much all modern online slots are video slots as most of them feature video and audio effects as part of the gameplay.

3. Progressive Jackpot Slots

As mentioned earlier, progressive jackpot slots are a set of interlinked slots games that all share the same top prize - the progressive jackpot. The jackpot is increased every time someone spins the reels on a connected slots game. There is usually a ticker above the reels that keeps a count of the jackpot value and you can see it going up. To hit the jackpot you usually need to match specific symbols on the reels or unlock and win a bonus game.

The best sites for progressive jackpot slots are 888casino and Dream Vegas.

4. Classic Slots

Classic slots are a throwback to the old days of Las Vegas gambling with row upon row of one-armed bandits. They have three reels and use traditional symbols such as fruit, bars, diamonds, and lucky 7’s. They usually don’t have any bonus features or fancy bells and whistles. They are available as online slots for people that want a simple, no-nonsense slots experience.

The best sites for classic slots are Grosvenor Casino and LeoVegas.

5. Mobile Slots

Mobile slots are simply online slots that can be played through an app on a mobile device. Many online casinos have a mobile app available for download these days, from the Google Play Store for Android devices and the Apple App Store for iOS devices.

In fact, some new online casinos are mobile-only which means that they are only available through a mobile casino app and not through a browser.

Free-play or Free Slots Games

Sometimes referred to as play-money slots, these are slots games that don’t use real money for wagering. The reasons to play free-play slots are either purely for fun or to practise playing on a specific type of game for free before wagering real money.

In other words, free slots games give you a chance to try out slots games with zero risk - you can’t lose any money when you’re in free-play or demo mode. At many sites, you don’t even need to register for an account to play the demo mode or free slots.

Another way to try the slots games for free is to look for the sites that offer a no-deposit bonus (explained in the section above), as this allows you to play with the bonus money and not real cash.

Online Slots Bonuses and Promotions

If there’s one thing that online casinos do well, it’s promotions and bonuses - especially when it comes to online slots.

Online slots are very, very popular with players, which is why the online casino sites are keen to offer lucrative bonuses to attract new players and run regular promotions to keep players loyal.

Here is a rundown of the most common types of bonuses and promotions for online slots that you can find out there and where to find them.

Welcome Bonus - Deposit Match

The welcome bonus is only open to new players that register at an online casino and players can only claim it once. A deposit match bonus is a welcome offer that gives new players a bonus that matches (or sometimes doubles) the amount of their first deposit (or first two or three deposits).

One of the best-matched deposit bonuses available at an online slots site at the moment is with The Grand Ivy which offers a 100% match bonus up to the value of £1500 (spread over the first three deposits), plus 100 bonus spins.

Welcome Bonus - No Deposit Slots Bonus

As online casinos compete more and more fiercely with each other to get new customers, no-deposit welcome bonuses are becoming increasingly common. As the title suggests, these welcome offers don’t require any deposit, you simply need to register for the site and verify your ID to qualify.

The best no-deposit welcome bonus at the moment is available at 888casino where they give you £88 worth of free play credits.

Free Spins

Free spins can be offered as part of a welcome bonus or as an offer to existing customers. There is no deposit needed, but they usually have wagering requirements attached to them to release any winnings.

In other words, you usually need to wager between 20 and 50 times the bonus amount before you can withdraw the winnings as cash.

No Wagering Bonus Spins

These are sometimes referred to as no wager free spins and they are the best time of “free spin” as you don’t need to meet any wagering requirements. This means that any money you win by using the bonus spins is yours to keep and you can withdraw it right away.

Reload Bonuses

Reload bonuses are bonus spins or deposit match bonuses that are given to you when you reload your account, i.e. make another cash deposit into your casino balance. Reload bonuses are usually run as occasional special offers that are time-limited, rather than ongoing promotions.  

Slots Tournaments

Slots tournaments are fun promotions that have a set prize pool to be distributed amongst players that score highly on a leaderboard. During the set time of the tournament, players score points for money won or money staked. The prizes are usually heavily weighted towards the top one, two, or three players.

William Hill, Bet Victor and Virgin Casino are recognised as the top 3 casinos for online slots tournaments.

Popular Online Slot Providers 

Irish slots casinos are likely to feature games from a wide range of providers. Some companies are better known than others, but even smaller developers can produce fantastic slot games.

With that in mind, here are 10 of the most popular slot providers at Irish online casinos right now:

Microgaming: Claiming to have developed the world's first true online casino software in 1994, Microgaming has long been one of the industry's most important companies. Microgaming was also a pioneer in the launch of the first mobile casinos, having launched its software in 2004.

NetEnt: Swedish studio NetEnt has been one of the most popular slot providers in the world for many years. Founded in 1996, NetEnt produces all types of casino games but has a strong focus on slots. Over 200 online slots have been released on to the market by NetEnt so far.

IGT: International Game Technology is one of the best known casino game providers in the world, with a long and proud history of slot development. IGT has been around for decades but the release of a new game from this slot provider still provokes a lot of excitement.

Novomatic: A range of video slot classics are available from Novomatic, with Book of Ra, Sizzling Hot and Lucky Lady's Charm some of the company's biggest hits to date.

Playtech: Founded in 1999, Playtech is now one of the most popular slot providers in the world. At the end of 2019, Playtech launched an industry-first, with its Live Slots potentially offering a glimpse of the future of online casinos. Age of the Gods: King of Olympus is one of the best Playtech slots that is available to play at online casino sites in Ireland.

Play'n GO: Specialising in high variance slot games, Play'n GO has grown into one of the most popular slot providers around over the course of recent years. Play'n GO titles include the huge Rich Wilde series, which has spawned a wide variety of imitations across the industry.

Pragmatic Play: A leading provider of slot game content for online casinos, Pragmatic Play hits include Wolf Gold and Dog House. Despite only being founded in 2015, Pragmatic Play games can be found at most of the top online slots sites in Ireland, with the company continuing to grow.

Yggdrasil: Slots from Yggdrasil are known for their incredible design, with progressive jackpot games among those produced by the developer. ‎Valley of the Gods is one of the top online slot games to have been released by Yggdrasil, with Holmes and the Stolen Stones up there too.

Quickspin: Another Swedish studio operating at the top of the online slots industry is Quickspin, a company that focuses on quality rather than quantity. This means that Quickspin does not release nearly as many new slot games as other providers, but they are always worth trying.

Realistic Games: Last on our list of the best online slots providers is Realistic Games, a leading casino content developer. Realistic Games is the company behind the hilarious Hot Cross Bunnies game, with the UK-based firm also producing games like Take Note.

Online Slots - Winning Strategy & Tips

Although online slots rely on random chance, there are some things you can do to try and increase your chance of winning or at least limit your losses.

Check out the following list of tips to help you get the best value for money when playing online sites in the UK.

Take Advantage of Sign Up Offers

The best way to make a bit of extra money when playing slots is to find the best welcome bonuses and make sure you claim them. Whether it’s a deposit match bonus or free spins, it’s always worth trying to get hold of this free cash that is offered to new players.

Just be aware that most welcome bonuses have wagering requirements attached, which means you have to bet a certain amount on the site before the bonus is turned into cash. Look for the welcome bonuses that have no or few wagering requirements. No deposit bonuses are good too, as you don’t need to spend a penny of your own money to get a chance of making some winnings.

Define and Use a Stop-Loss Strategy

This is a more practical tip that you need to implement before and during playing. First, you need to decide how much you are willing to lose in any one session. This is not necessarily the total amount you can afford to lose, it could be the amount that is going to really annoy you and make you want to chase your losses.

Write down the limit and keep it in mind while you are playing. If you reach the stop-loss limit, let’s say £30, then you log off straight away and stop playing. You can decide how long to stop for, whether it’s a ten-minute break or stop for the day, or even week. If you stick to this strategy it will stop you from chasing your losses and should limit the amount you lose overall.

Define and Use a Stop-Win Strategy

Similar to the stop-loss strategy laid out above, the stop-win is exactly the same, but you set a limit for the amount of profit you’re in. When you get to that maximum limit you stop and take a break - ten minutes, one hour, a day - whatever you decide.

The reason for setting a stop-win limit is that it’s all too easy to feel like you’re invincible and can’t lose. Many people will then start playing at higher stakes and quickly lose all their winnings. You need to avoid this at all costs.

Set a Time Limit

Another way to limit your losses and maximise your winnings is to set a strict time limit for playing the slots. It’s easy to get carried away and play for hours upon end, but this can possibly turn into irresponsible gambling if you’re not careful. Set an alarm on your watch or phone for 30 minutes, or however long you’re willing to play, then be disciplined enough to stop when it goes off - whether you’re winning or losing. 

Only Play High RTP Slots 

Use our lists of high RTP slots and slots sites above to help you choose games that offer the best return on your money. This will help to make your bankroll last a bit longer and give you more chance of hitting some big wins.

Play the Maximum Number of winlines on Progressive Jackpot Slots

This applies to most slots sites - you cannot win the maximum amount of the progressive jackpot if you don’t play at the full stake. In other words, if you only play one winline when there are ten available and you hit the jackpot, you’ll only win 10% of it. Not everyone is aware of this fact.

Frequently Asked Questions

How do online slots work?

Online slots involve betting on the outcome of spinning reels. You place a stake on your chosen number of win lines and click a button to spin the reels. The slots game uses a random number generator (RNG) to decide where the reels stop spinning. The software then looks for matching symbols across the win lines to see whether you win any money or not. Most online slots have wild card symbols that can stand for any other symbol.

Sometimes you may get the correct alignment of symbols to unlock a bonus game or feature. The bonus game may give you extra winnings, free spins, or even a chance at winning the jackpot or progressive jackpot.

What online slots pay real money?

Online slots at UKGC-licensed online casinos in the UK pay real money. Any slots game on these sites that you wager real money on will pay out in real money. The only exception is when you get free spins, as sometimes these will be paid out as bonus money which must be released by meeting certain betting requirements, i.e. placing more money on spins until you reach the qualifying amount.

How to play slots online?

To begin with, you need to open up an account with an online slots site in the UK. To do this you need to register your details, then verify your identity using a scan or photo of an official government-issued ID document such as a driving license or passport. Then you can deposit money into your casino balance and use this to play the online slots.

How to play free slots online?

If you want to play free slots, you can look for sites that offer a “demo mode”, which means you can play the slots without betting any real money. This gives you a chance to learn and understand the slots game before you wager real cash.

The other way to play online slots for free is to look for sites that offer a no-deposit bonus (such as 888 Casino that gives new players £88 to play with in their casino). You can then use the bonus money to play the slots, rather than real cash.

Which slot site offers the best payouts?

Rainbow Riches Casino, 888 Casino, and Virgin Casino are the top 3 slots sites in terms of payout percentages. In other words, your money will last much longer and you have more chance of getting some winnings back at these sites compared to others.

Where to find no deposit slot bonuses?

The following slots sites and casinos offer no-deposit bonuses but only through exclusive bonus codes found on BettingGuide.com - 888 Casino, Unibet, William Hill, NetBet, and Betfair Casino.

Olivia Johnson

Olivia Johnson

Olivia is responsible for all content on BettingGuide UK. Olivia has a degree in journalism from Cardiff University and loves to play different casino games in her spare time. If you have any questions regarding online gambling in the UK, don't hesitate to contact her.

Last updated: 7/6/2021