Many people would love to have their lives transformed by hitting a huge jackpot with a lucky spin of an online slot. Progressive jackpot slots offer you the chance to do just this, with potential prizes that are simply out of reach with even the highest paying regular slots. 

Progressive slots take a portion of every stake made by players and add them to one or more jackpot prize pools. These build up as people play on the slot, until the jackpot is triggered.

In this article, you’ll see how progressive jackpot slots work, see some of the biggest jackpot wins, and find out how you can use progressive slots to your advantage by doing casino offers. 

How Progressive Slots Work

Jackpot Accumulation

Progressive jackpot slots work a little differently to regular slots, by taking a portion of your stake and adding this to a jackpot fund. The screenshot below shows Mega Moolah, which is an example of a progressive jackpot slot:

Not taking into account the jackpots, Mega Moolah has a very low Return To Player (RTP) of 88.12%. On top of this, there’s an additional jackpot contribution of 5.30% of your stake, meaning that for every £100 staked, £5.30 is added to the jackpot fund.

This fund is shared between the four jackpots – Mini (red), Minor (orange), Major (yellow), and Mega (white). In the screenshot, the value of the Mega Jackpot at the top left is £3,620,256.83 at the time. Funded by the 5.3% jackpot contributions, this jackpot builds up until a lucky player eventually wins it.

Networked and Standalone Progressive Jackpot Slots

There are two main types of progressive jackpot slot: standalone and networked. A standalone progressive slot accumulates the jackpot fund from just one machine or a single slot on an online site. 

Networked progressive jackpot slots work a little differently. These link multiple machines or slots, sometimes across different casinos or casino sites, all of which share the same jackpots. 

Because there’s far more money being put into networked progressive slots, the jackpots grow much faster. You’ll tend to find that online progressive jackpot slots are networked slots. 

The screenshot below shows different Mega Moolah slots at a particular casino, all of which share the same jackpot fund:

Jackpot Seed Money

When a player of any of these slots across all of the casinos that host them wins one of the jackpots, the jackpot amount drops to a minimum amount. The Mega Moolah Mega jackpot resets to £1,000,000 after being won, for example.

This minimum amount is known as the seed amount, and it’s guaranteed and provided by the casino or slot provider. After being re-seeded at this minimum amount, the jackpot starts to grow again, funded by players’ jackpot contributions as before.

Random Number Generators (RNGs)

Like all online slots, progressive jackpot slots use Random Number Generators (RNGs) to generate their results and ensure fairness. Since each spin is independent from all other spins, RNGs make it impossible to predict when a jackpot will hit.

How Are Jackpot Wins Triggered?

Online progressive jackpot payouts can be triggered in several ways:

• At random, using the slot’s Random Number Generator (RNG).
• By hitting a particular payline, for example, a line of special symbols.
• By activating a bonus feature. From within this, you might need a certain outcome on a prize wheel or pick three matching jackpot symbols from a set of hidden symbols.

Mega Moolah has a randomly triggered bonus round that can happen after any spin, independent of the payline you’ve landed on. If you hit the bonus round, you’re presented with the following screen:

The bonus round features a prize wheel with red, orange, yellow, and white zones for the four different possible jackpots. To win the Mega Jackpot, the wheel needs to stop with the pointer over the white zone with the image of the paw, as shown below:

Here’s a screenshot of Mega Moolah’s demo or free play mode, showing what would happen if you won the Mega jackpot:

Jackpot King Slots

Another popular provider of networked progressive jackpots is Jackpot King. With these slots, the jackpot is triggered by hitting a specific winning payline – a line of Jackpot King symbols.

This can be triggered randomly on any spin and at any stake size. You can see what this looks like on the Luck O’ The Irish Fortune Play slot below:

After entering the bonus round, the player then needs to activate the Wheel King to have a chance of winning the jackpot.

To hit the biggest jackpot, known as Jackpot King, the Wheel King needs to land on the ‘Jackpot King’ symbol. You can see what this looks like in the screenshot below, which shows a reconstruction of an actual £4.6 million UK jackpot win:

If you’re lucky enough to ultimately hit the Jackpot King, you’ll be greeted by a screen informing you that you’ve just become several million pounds richer than you were a few seconds ago.

It’s worth pointing out that, even if you’ve made it through to one of these jackpot bonus rounds, you’re still very unlikely to come away with a huge profit.

To temper your expectations a little, here’s a screenshot of a ‘massive’ £1 win from one of my own Jackpot King bonus rounds, which I hit whilst wagering for a casino offer:

The Biggest UK Progressive Jackpot Wins

The table below shows the biggest UK jackpot winners, including the amount of money they won and the equivalent value as of the writing of this article, as of November 2024.

Using Progressive Slots For Casino Offers

Although it’s great to think about the possibility of hitting a huge jackpot win on a progressive jackpot slot, the chance of doing so is sadly extremely small. 

In reality, the vast majority of players of slots, progressive or otherwise, will just lose money in the long run. This is because all slots have an RTP (Return To Player) under 100%. 

For example, Mega Moolah has an overall RTP of 93.42%, including the jackpot contribution, meaning you’ll only get £93.42 back on average  for every £100 wagered. Putting it another way, you’ll lose an average of £6.58 per £100 wagered.

However, there is a way to make long-term profits from progressive jackpot slots, and that’s by using them to complete casino offers.

Here’s an example of a Betfair Casino offer at Oddsmonkey, which uses a Jackpot King slot for the initial wagering and free spins:

You get 50 free spins initially, then another 50 after completing wagering. 

The expected value (EV) is the average profit you’d make from the offer if you did it hundreds of times. Here’s how it’s worked out, using Eye of Horus Jackpot King, with its RTP of 95.46%:

• Average remaining money after wagering £10 at 95.46% = £10 x 0.9546 = £9.546
• Average loss from wagering £10 = £10 – £9.55 = £0.454
• Average profit from 100 spins at £0.10 each on a 95.46% RTP slot = 50 x £0.10 x 0.9546 = £9.546
• Expected Value (EV) = Average profit from offer = £9.546 – £0.454 = £9.09

It’s much easier to work this out using Oddsmonkey’s handy EV Calculator:

The great thing about using a progressive jackpot slot for this offer is that it has great long-term value, but there’s also a small chance you could have a life-changing win. 

Having said that, when it comes to completing casino offers, progressive jackpot slots won’t always be eligible. Even if they are, they often have quite a low RTP, so a regular slot will often be the better option to maximise your EV. 

Summary

The appeal of progressive jackpot slots is obvious: alongside the hope of a decent win and making a nice profit, there’s always the chance you’ll hit one of the big jackpots for a life-changing win. 

As with all slots, if you’re purely gambling on them, unless you happen to be incredibly lucky, hit a big win, then stop playing, you’ll lose money in the long run. This is because the RTP of slots is always less than 100% (they pay back less to the player on average than the amount staked). 

If you want to use slots to your advantage, doing casino offers with Oddsmonkey is the way to go. Although you’re not guaranteed to make a profit from any offer, as long as you keep going with +EV (positive expected value) offers, you’ll make profits in the long term. And the more offers you do, the more money you’ll make.

Whilst doing casino offers, it’s very important to follow the guides to the letter and avoid doing any additional spins. Not only do these extra spins reduce your long-term value, they can be the first step to getting carried away and developing a gambling issue.