18+ | Play Responsibly | Wagering requirements and T&C’s Apply | Commercial Content | Advertising Disclosure
Lucky Street is an independent professional comparison site supported by referral fees from the sites which are ranked on this site. The sites and information we present are from companies from which Lucky Street receives compensation. This compensation may impact the rankings of the sites. Other factors, including our own opinions, your location, and the likelihood of signing up, may also impact how the ranking of the sites appears to a particular user. Lucky Street cannot and does not present information about every casino site or casino site offer available.

How Do Online Slot Machines Work?

United Kingdom

Legal casinos in

United Kingdom

Reviewed by our Experts

Updated on

Reviewed on

Slot games have boomed in popularity in recent years, taking the place of more traditional table games, thus knowing how online slot machines work is always beneficial. They are easy to find in many online casinos, very simple and easy to play, and come in all sorts of themes and designs.

LeoVegas Book of Dead

More advanced video slots even come in 3D, with their own stories, excellent graphics and next level audio, making them the perfect addition to online casinos and paving the path for a new generation of high-tech online gaming.

Today over a million people play online slot games, making them one of the most popular casino games in the world. They also account for the majority of casinos’ generated profit – which is a guarantee that slots will just keep getting better and better.

It also means that casinos can become more generous with slots payouts – with most slots having a payout percentage between 90 – 97%.

Many of us enjoy browsing through these seemingly never-ending collections of slot games and playing all sorts of different slots for hours. But how do these slot machines work?

Where Do I Start?

Slot machines are attractive to a lot of gamers because they don’t require any previous gambling knowledge or skill – most of the time, it’s just a matter of pushing a button or pulling a lever.

But although it’s not necessary to know exactly how a slot machine works in order to get the hang of playing it, it doesn’t hurt to know the exact mechanics, either. Get familiar with the game Starburst by collecting the various no deposit free spins offers for it!

But although it’s not necessary to know exactly how online slot machines work in order to get the hang of playing it, it doesn’t hurt to know the exact mechanics, either.

In fact, those who know absolutely nothing about slot machines run the risk of believing some common myths about how to win at slot machines, or make use of fake strategies. We’re here to explain to you in detail just how online slot machines work.

The Basics Of How Online Slot Machines Work

Slot machines in the past were mechanical – functioning according to an arrangement of gears and levers. After inserting a coin, the handle unlocks due to a coin detector system. Inside the machine one would find a metal shaft supporting the reels and connected to a handle mechanism.

The handle sets everything in motion, while a braking system causes the reels to stop after they are pushed into spinning. The payout system picks up on the symbols and initiates the payout depending on the value of these symbols.

Once video slots appeared to the scene, these complex mechanics were replaced by microchips, now operating from the motherboard of the machine. Slot machines work because of a computer of sorts inside it, making use of the computer’s Random Number Generator (RNG).

The computer runs according to step motors which turn each reel, as well as cause it to stop where it is meant to. Step motors are moved by digital pulses from the computer, unlike how mechanical slot machines work – through the use of an electric motor.

How Slots Work Now

Nowadays, online slots are specifically designed by software providers who build upon the mechanics of a classic slot machine, with more sophisticated design and functionality. Many of the same aspects remain, however, such as the simple game controls and RNG.

Most slot machines, whether they are mechanical or computer-controlled, physical machines or online slots, have the same basic controls: pulling a lever (or pressing a button) to spin the reels (originally three, but modern online slots usually have more). These reels contain symbols, and if the same symbols line up on a payline, it’s a win.

Typically, different symbols carry different values, so how big your payout depends on which symbols happen to line up. In the case of many online slots, your payout also depends on how high your bets were on these particular paylines.

The Facts About How Online Slot Machines Work

Some online slots might feel exactly like traditional slot machines, but they actually function very differently. Whilst slot machines in land-based casinos give you the result through typical electric motors causing the reels to move, the result of online slots is determined by a random number generator through a computer software.

Don’t let this fool you, though – online slots are not programmed to scam you. Random number generators (RNG) are a secure way to ensure fair gaming, and their use is monitored by the casino’s license. RNGs are a guarantee that your outcome will be completely random, and there’s nothing you can really do to turn a slot machine in your favour.

Big Payout Slot Machines

Of course, this doesn’t mean that certain rules are thrown out of the window – with online slots, there are many ways to increase your likelihood of getting a big payout, such as betting on the maximum amount of reels.

In fact, you can utilise a number of tips and tricks to make sure you get the most out of your deposit. For instance, you can go that extra mile and do some research on which slot games will suit your specific aesthetic tastes.

Always look for games that have promotions attached to them, or come with the most generous bonus rounds. However, outside of these tips and the rules of probability, winning at slots is largely a matter of luck.

Great welcome offer for UK slot players

LeoVegas Sign Up Offer

99/100 Expert Review
50 FREE SPINS & up to £100
      18+, GambleAware.org., Full T&Cs apply.. New reg only. Opt in & deposit either £10, £25 or £50 within 7 days & further 7 days to wager your deposit 35x to unlock reward (up to £50 for each of your first 2 deposits). Wagering/game contributions vary. 25 x 10p wager-free spins added to Big Bass Splash with each qualifying deposit, 3 day expiry. Other Promotional Play Restrictions Apply. T&Cs apply. GambleAware.org

      How Payouts Work

      One thing that computer software are able to do, though, is to adjust how quickly a slot machine will pay out. This is why different slot machines have different payout percentages, and why certain slots are described as “tight” while others are “loose”.

      Although you might have heard the term “payout percentage” often, few gamers know exactly what it means. A payout percentage is the percentage of money that eventually ends up being paid out – for example, a slot with a payout percentage of 93% means that the slot takes away 7% of all the cash deposited to it, and give away 93%. This gives the casino an advantage in the long run, and is the reason why slot machines remain profitable.

      However, it is usually in the casino’s best interest to keep their payout percentages relatively high in order to remain competitive. In fact, payout percentages for slots can go up to 98%, though finding one like that is pretty unlikely! Most are around the 95% range, like Thunderstruck II.

      Slot Machine Payout

      Once a payout percentage is set for a slot machine, it is not easy to change it. Most slot games have consistent payout percentages that never change, in fact, not even over time.

      This is a vital characteristic of the way slot machines work – playing for longer does not mean that the likelihood of winning, or the amount to be won, will increase. Due to the random number generator, your odds don’t change, and the outcome is entirely random.

      However, online slot machines come in two types: straight slot and progressive slot. The payout for a straight slot never changes, while that of a progressive slot increases as you input more money. This amount steadily increases up until the jackpot is won – then the amount is back to zero.

      Unfortunately, no matter how well you pick your slots or your strategy, the slot machine will always have an edge over you. The payout is always lower than the odds of winning, and this system allows casinos to make their profit.

      Slot Machine Works through Random Number Generator

      In a sense, traditional slot machines also used a random number generator. However, this RNG was mechanical, whereas modern slot machines, including online slots, use a computerized system for generating a random outcome.

      It might feel like it sometimes – but online slots are not pre-programmed to be cyclical, or to get “hot” or “cold”. The symbols are selected by computer microchip, but this is done in accordance with the casino’s policy on fairness.

      All online casinos must be licensed and tested for fair play, so there is nothing to worry about when it comes to trusting the RNG.

      Slot games have come a long way, but in terms of their mechanics – they haven’t changed that much. Some sceptics tend to avoid slots due to their suspicions regarding the fairness of online slots, but tends to be because they don’t understand the way that slot machines work.

      The RNG is an extremely effective system that picks random numbers at a rate of one per millisecond, ensuring fairness and giving you a decent chance of scoring a win.

      Throughout the entire evolution of slot machines, the RNG stuck. This is because it is the most effective way to ensure very quick outcomes and a truly fair game.