How Do Slot Machines Work?

They say that information is power, and I for one can attest to the fact – especially when it comes to pokies, slot machines and Casino Slots – even though granted they are all technically the same thing. But understanding how slot machines work can provide you with the knowledge needed and the insight required to better your chances, increase your odds and ultimately figure out How to Win on Slot Machines – or at the very least pick the best slot machines to play so your chances of a win and overall enjoyment factor increase dramatically.

how slots and pokies workLet’s start by looking at Slot Machines from a superficial perspective – because what you see and what you get are quite independent of each other, meaning the trick here is to look past the flashing lights, music and hypnotic feature enticers to the game itself – because the more you can understand the game itself, the paylines, the bonus options, features and any other variables – the more chance you have of actually winning something – or at least maximising your chances…

Looking At Slots Superficially – What’s To See?


When looking at the physical components of a modern day slot machine it is not uncommon to be overwhelmed by all the requirements and technical specs – but the only thing to note here is that regardless of how many bells and whistles the slot machine has, it’s what’s inside that determines the rate, frequency, and amount that you can potentially win with each ‘press’ or spin of the reel

When it comes to the inner workings of slot machines, the components can be broken into two areas – the reels themselves, and the computer algorithm controlling where and when they stop – and although at first glance it appears incredibly technical and way to confusing to understand, it’s actually quite straight forward and once you see it written as such you begin to realise why Casino’s and Clubs love the slot machines and the inherent edge it gives them over any and all players…

How Slot Machines Work – The Reel and Stop

how slot machines workSlot Machines usually come in 3 or 5 Reel formats – the reel of course being the images you see scrolling past when the button is pressed. It has multiple symbols on it, and if you line up certain combinations of symbols, you win money. The less likely it is to line up a particular set of symbols, the higher the payout on that particular combination.

For decades, these reels were literally large metal hoops, but now that slot machines are powered by computers, they’re more often just images on a video screen – although it is important to note that regardless of the format of these reels – the place where these reels ‘Stop’ is determined by a Random Number Generator – the computer side of the slot machine. But we’ll get to that shortly.

The Significance of ‘Stops’ within Slot Machines is quite high. Reels can stop on a symbol or on a blank space between those symbols. On early slot machine games, each symbol would have an equal chance of coming up, but now that computers are running the show, the odds can be convoluted. You might have a cherry on a reel that comes up on average once every 50 spins, while an orange might come up on average once every 5 spins, or any other combination you can think of – again this is all determined by weighting – and again we’ll touch on that shortly

Early slot machines might have only had 10 stops per reel, but now it’s common to have between 30 and 50 stops per reel. The more stops you have on a reel, the easier it is to offer really large jackpots. For example, if you have a game with 10 stops on each reel, with an equal chance of landing on each stop, then your chances of winning on any standard 5 Reel Slot Machine are 1/10 X 1/10 X 1/10 X 1/10 X 1/10 or 1/100.000.

The Casino could technically offer a $50,000 Jackpot on that combination and still guarantee to double their money – yet the players think this is an incredible opportunity and will happily gamble away their hard earned money for a chance at 50k in cold hard cash!

Understanding the Weighting System in Slot Machines

The weighting is what determines how likely a particular stop is to be picked. Suppose you have a slot machine game with 10 symbols, but one of those symbols is special and only comes up once every 100 spins. The odds of getting 3 of that symbol are 1/100 X 1/100 X 1/100, or 1/1,000,000. You could theoretically offer a payout of $1 million on that combination and still break even over the long run. Casinos love that kind of action, and so do players.

Another symbol might be programmed to come up half the time, so your chances of hitting that symbol might be as low as ½ X ½ X ½, or 1/6. If that pays out at 2 to 1, the casino still makes a significant profit, but the player feels like she’s winning on a pretty regular basis.

The par sheet determines the odds. Every modern slot machine is designed with a par sheet which specifies the weightings for each stop on the reel, including the blanks. That par sheet makes the odds and the house edge for a slot machine game a known quantity—for the casino. Gambling companies keep these par sheets under wraps, though, so players never really get a clear idea of what the odds, the house edge, or the payback percentage is.

How Slots Work – The Random Number Generator

The Random Number

how do slot machines work - RNGGenerator is the algorithm or program within the slot machine that determines where the reels will stop each time. The Random Number Generator works independently of any progressive or linked jackpots and is unaware of the overall odds of each ‘stop position’ All the Random Number Generator does is wait until someone presses the button or pull the handle – at which point the computer algorithm runs and generates the requisite amount of numbers (3 or 5 depending on how many reels you are playing) and determines where this is on the ‘reel’. This happens in a microsecond and the results are fed to the machine which stops the reel at the corresponding spots. The Slot machine then pays whatever is displayed on the resulting lines.

The image to the left shows a basic visual of how the process works, although some RNG’s work by dividing the resulting numbers – but so long as this division is consistent there is no issue with this method – highlighted in the image below for your information.

In terms of odds, keep in mind that although the RNG works independently of it, the fact that the odds are predetermined based on number of reels, stops and symbols in proportion to the pay lines means that even the RNG cannot influence it. All The Random Number Generator is told is what the RTP or Return To Player rate is – because as long as it pays out at the same rate it is doing it’s job

But What’s the Return To Player Rate?!….. I’m glad you asked actually…

how do slot machines work - RNG

Understanding Slot Machines – The Return To Player Rate (RTP)

One final term you should understand is ‘Return To Player’ Rate or RTP. This is the legal requirement and return rate at which slot machines must “pay back” or return to the player over an infinite number of spins. For example, if a machine is programmed to have a 87% RTP Rate, then the average should come close to winning $87 out of every $100 put into the machine. Casinos distinguish between the theoretical payback percentage and the actual return on the machine, but the fact remains that slot machines are one of the most profitable forms of gambling for online and real world casinos alike.

Return To Player Rate for Australia

The return to player (RTP)rate is determined by legislation and is different for every state and territory. Right now, the percentages look like this:

ACT – 87%
NSW – 85%
NT – 85% for clubs, 88% for casinos
QLD – 85/92% for clubs/pubs, 90% for casinos
SA – 85% for games installed before 1/10/01, 87.5% for games installed after 1/10/01
TAS – 85%
VIC – 87%
WA – 90% (casino only)

Something important to note is that although the advertised payout rate may be 90% (for example) – the actual rate of return is slightly lower as at least 1 or 2% of this RTP Rate is reserved for the linked/progressive/accumulative Jackpot that many modern day slots and online pokies are connected to. – Read more here to get further insight into what we refer to as ‘The Great Jackpot Swindle’

return to player rate for australiansFurther Reading and Resources:

Learn more about how slots work and specifically what the Return To Player and Payout rates are for slot machines and other casino games at – How Slot Machines Work

Get a better understanding of the games involved and more importantly, the etiquette associated with playing the slots – online and in real world casinos – How To Play Slot Machines and Casino Slot Games

Finally – use your smarts to increase your odds and improve your gameplay on any slot machine you pick  – check out our genuinely useful Slot Machine Tips and win at slots today!