There are a number of factors to keep in mind when you want to find the best payout slots online. These include:

• The size of the jackpot - You’ll find the biggest prizes attached to progressive slots, because the more that people play, the faster the jackpot builds.

• Play popular titles - Look for games with a decent track record of rewarding five or six-figure prizes, rather than titles offering a huge prize that is only won every year or so.

• Check the return to player (RTP) percentage - This will tell you what the house edge is on the slot. For online slots, an RTP of 95% or higher is favorable.

• Find out the maximum stake - The best payout online slots tend to be those with the highest maximum stake, and in many cases, you need to be betting the maximum to scoop the jackpot.

• The number of paylines - Some high-payout slot games feature tons of paylines - sometimes over 1,000! For players prepared and financially able to cover all lines, there's more potential for bigger payouts.

RTP stands for return to player percentage. When applied to online slots, RTP is a figure that lets you see the house edge on a particular game at a glance. For example, if the RTP is 95%, that means for every $100 you wager on that game, you can expect a return of $95 on average. Details of a game's RTP can be found in its paytable.

It’s also worth noting that the highest-paying games tend to offer the lowest RTP. For example, the RTP of one of the world's most famous progressives, Mega Moolah, is 88%. When choosing which game to play, make sure to balance the prospect of a big win against the RTP first.

More information on online slots games are available on the pages below:

• Classic Slots
• Bonus Game Slots
• Multi Payline Slots
• Fruit Machines

If you’re looking for the highest paying online slot machines with high RTP rates and big jackpots, we recommend the following titles:

1. Mega Moolah, Microgaming: RTP of 88%
2. Mega Fortune, NetEnt: RTP of 96.6%
3. Immortal Romance, Microgaming: RTP of 96.86%
4. Book of Dead, Play'n GO: RTP of 96.21%
5. Gonzo's Quest, NetEnt: RTP of 96%

Here are some of the highest payout slot machines you can find online, created by a selection of our favorite software developers:

Amaya

Amaya is relatively new to jackpot slots, but its Millionaires’ Island, a progressive slot that guarantees a minimum $1 million jackpot, was launched in January 2017 and became a big hit with online slots players.

Aristocrat

Australian company Aristocrat was one of the pioneers of progressive jackpots thanks to its Hyperlink technology. Its main progressive jackpot games with the biggest payouts include Cash Express and Jackpot Carnival, which have both produced regular big wins.

Bally

Bally has two games that are well known for having high payouts. Thunderhorn boasts an impressive 1,024 pay lines, and Hot Shot is a classic fruit machine style game that has a potential payout of 10,000 times your stake.

IGT

International Gaming Technology (IGT) is one of the world’s biggest creators of online slots, and its slot machines with the biggest payout potential are part of its progressive jackpot series of Mega Jackpot games, which has an average jackpot payout of $2 million!

Microgaming

The most popular progressive jackpot slot game by Microgaming is Mega moolah, which has paid out numerous life-changing sums over the years, including a ￡13.2 million payout to a Betway Casino player in the UK in 2015.

NetEnt

Leading casino games software developer NetEnt has a range of progressive jackpot games that offer huge payouts, including Hall of Gods Mega and the famous Mega Fortune. Its jackpot slots paid out a combined 78.3 million Euros to lucky players in 2017 alone!

Novomatic

European gaming company Novomatic has a handful of online slots with progressive jackpots, such as Elven Princess, King’s Treasure, Jolly Reels, and Golden Sevens, all of which have produced a string of six-figure payouts.

Play’n Go

While Play’n Go hasn’t placed as much emphasis on progressive jackpot games as other providers, its online slots with the biggest payout potential include Gunslinger and Fruit Bonanza, which are known to generate five and six-figure payouts.

Playtech

Playtech has a large collection of progressive jackpot games. The most famous of which is Beach Life, which has an average jackpot win value of $2.5 million!

Real Time Gaming

Real Time Gaming (RTG) is responsible for some of the world’s most popular games with good RTP rates, including Aladdin’s Wishes, Aztec’s Treasure, and Cleopatra’s Gold. In terms of life-changing jackpot potential, its best slot is Aztec Millions, which is known to pay out millions.

We consider a variety of factors when compiling our casino reviews, but how exactly do we determine which casinos and slots have the best payouts?

• Game selection - We assess the range of classic and video slots, video poker, table games, craps, and live casino games. A good online casino should have hundreds of high-quality games, with a great selection of slots from reputable software developers, like Microgaming, NetEnt, WMS, IGT, and many more.

• Casino and slot machine payout rates - We take note of each online casino's audited online payout rate to make sure the house edge is fair. The online slots are then examined to make sure the casino has online slots with high RTP rates and big jackpots.

• Safety and customer support - Security systems, official licensing, and game regulation are essential to ensure the safety and fairness of an online casino. We also evaluate the efficiency of customer support, make sure they’re easily contactable, and provide fast response times.

• Bonus offers and rewards - Casinos must offer sign-up bonuses, free spins bonuses, reload bonuses, and promotions with fair wagering requirements. We see what bonuses are on offer and read the terms and conditions to make sure they’re actually attainable.

• Mobile compatibility - Since more gamers are enjoying playing casino games on mobile, the casinos must have a mobile-friendly version of the website, and/or a dedicated app, with games that are optimized to run seamlessly on modern smartphones and tablets, including iOS and Android devices.

• Banking options - Online casinos should offer a variety of popular banking methods, including bank cards, bank deposits, e-wallets, and even cryptocurrencies. Deposits should be instant, and withdrawals should be fast with low or no transaction fees.

Online slots have triggered plenty of headline-grabbing slot machine wins over the years, with payouts so staggering it would make you look twice!

One of the biggest payouts for online slots came in January 2013 when an anonymous player from Finland won 17.86 million Euros playing NetEnt game Mega Fortune.

However, in 2015 a player from the UK topped that figure when he won ￡13.2 million playing Microgaming's Mega Moolah, which, due to the exchange rate, earned him the Guinness World Record for the largest online jackpot payout.

Plenty of millionaires have been created through online slots since then, but not quite the amount of millions that these lucky players received.