Online slot terminology: Know your +EV from your RTP

Learn about RTP and EV and slots terminology

Like almost any aspect of life, once you become something of an expert on a particular subject then it is very easy to lapse into the vernacular of your chosen subject. Many professions, for example, use a wealth of acronyms when discussing an issue and these can be hugely confusing to someone learning about the subject or listening in for the first time.

Slots gaming is no different, once you get beyond the very basic 'place your bet - spin the slots' understanding of the games. Once you delve behind the slot itself and take a look at the key mechanics of the game, how the game works and your chances of winning on the slot, then the terminology can be somewhat confusing.

Add to this the terms used by people who discuss slot games and similar as part of 'game theory' as it has become known, and when you read some slot reviews, you can be forgiven for thinking that they don't seem to be speaking about a slot game at all.

So if you are not sure if your preferred variance is high middle or low, if you don't know the difference between a -EV and a +EV and if you think that RTP is the latest Suzuki sports model, then this article is for you!

Assumed knowledge

To begin this article, I am assuming that you have a basic understanding of slot games and how they work. By that I mean, you know you wager your cash and hit the spin button. I'm also assuming you know what terms like Free Spins, Wild, Scatters mean and how they can manifest themselves in slot games.

I'm also assuming that you know what a progressive jackpot is compared to a standard jackpot, as well as that on many slots you need to place a stake on each line you want in play.

What we are going to do in this article is go beyond this initial working of the slot and look into some of the more detailed terms used by more experienced (or expert if you prefer) players. These terms tend to do with your chances of winning on the slot, whether you are getting good value for money playing the slot.

Let's begin with the simplest of these to understand.

RTP - Return to Player

When you read a review of a slot game you will often see a figure quoted next to RTP. What does that mean? Well RTP stands for Return to Player and the percentage quoted is the amount of money that the slot takes in, that it repays back out to players over time.

I've often seen RTP of, say 97%, explained erroneously as "for every $100 the slot takes in, it will pay out $97". This is absolutely not the case. What RTP means is that over a considerable length of time (and we're not talking hundreds or thousands of spins here, but more likely millions or billions), the slot will on average pay out $97 for every $100 taken.

However, within that, the slot will sometimes pay out far less than $97 per $100 spend and at other times, if you get lucky, it may pay out considerably more than $97 per $100 spend.

RTP does not mean that if you spend $100, you will get $97 back guaranteed. How much you get back can vary greatly and this is where we now need to understand the concept of variance and how it links in with the RTP percentage rating.

Variance - High, Medium and Low Variance Slots

The variance of a slot (also sometimes known as its volatility), is also to do with pay outs and often many beginners confuse variance with RTP thinking they are one and the same thing. They are not.

RTP gives you an indication of how much typically a slot will pay out compared to the money it brings in over an extended period of time. Variance however looks at precisely how that slot pays that money out.

To understand variance, we are going to use some extreme examples that are not indicative of slot games in the real world, but which will illustrate the concept most easily for the lay-person to understand.

Let's assume that a slot has an RTP of 95%. Now let's assume that our chosen slot has played through a million $1 spins. Bringing in $1,000,000 and that it has duly paid out $950,000 in cash (of course a real slot game would never be this uncannily accurate). The variance of the slot would determine how that $950,000 is paid out.

A lower variance slot would see more lower value wins paid out, so in this example, a very low variance slot would see several hundred thousand individual wins of $1, $2 or $3 apiece, with just a couple higher value wins.

higher variance slot would see a much smaller number of lower value wins, but it would also see a small number of much higher value wins. For example, in our imaginary slot, its $950,000 could be paid out in 50,000 wins of $1 and 18 wins of $50,000, or for ultra-high variance, maybe just one win of $900,000.

For a medium variance slot, the pay outs achieved would sit in between the Lower and Higher variance amounts, so you would still have a decent number of lower value wins, considerably more medium value wins and a couple of higher value wins.

The key things to remember with RTP and Variance is that RTP tells you on average how much the slot pays out over a lengthy period of time, and variance indicates how the slot tends to pay that money out (either in lots of smaller wins with fewer larger wins, or fewer smaller wins with slightly more larger value wins).

Positive and Negative Expected Value

Once you have an understanding of RTP and Variance, then the next thing you may start looking at on a slot is the mechanics and mathematics behind the game. Many slot players tend to glaze over at this point and they are happy to play their games without delving too deeply into the nature of randomness and chance, but for others who take a more scientific approach, they want to know the optimum time when a slot should be played.

That may sound counter-intuitive. Slot games are based on random number generators and randomness has no pattern to follow, so how can you predict when a slot is worth playing, compared to when it is not?

The key to understanding this is not that you are playing a slot at an optimal time to win, but that you are playing a slot so that if you win (and 'if' is the key word here), you should get a better than average return on your investment. This is called a positive expected value and is often expressed as +EV. The opposite is when you don't get as good a return on your spend and this is a negative expected value (-EV).

There is a mathematical process to work out the expected value of a slot and it is to multiply your chances of winning on the game, compared to the largest amount of money you could win when playing the slot, minus the investment you need to make to win the prize.

However, you don't need to get bogged down in mathematics as you can ensure you get the best EV on your chosen slot by following a simple rule:

  • If you've got lots of money to spend - play higher variance slots
  • If you have a smaller bankroll - player lower variance slots

When slots can offer you +EV

Now on standard slots, this is not possible to alter as the jackpot on a standard slot game remains the same at all times. So, on all standard slot games, you are only going to get -EV. That's not a fault of the game, it is a necessity as if all standard slots had +EV, then casinos would lose money on each of the games and quickly go out of business.

However, the randomness of slot games means that even slots that have -EV, still can offer you a profit if you are lucky enough. It's just the chances are, they won't. Slot players are happy to accept those odds when they play any game.

That changes when it comes to progressive jackpot slots. In these games, progressive jackpots can grow in size with every spin made on the game. As a result, the size of the jackpot can grow and at some point, it will reach a point where the amount of money you win, will ensure that you have a +EV outcome on the slot.

What that amount is differs from slot game to slot game. On Mega Moolah for example, the +EV amount runs into the multi-millions, on other progressives with smaller prizes, the +EV for these games is proportionally much smaller.

What you will find is that when a progressive starts to offer +EV for players, the number of players that start to play it will increase and this can subsequently lead to a dramatic increase in pace in how quickly the jackpot fund increases in size.

RNG - Random Number Generator

The RNG is the beating heart of a slot game and without out, slot games would still be back in the days of mechanised three and five reel slots offering small jackpot wins. RNG stands for Random Number Generator and it is this which performs the crucial function of deciding how the reels will land whenever you make a spin on a slot game.

A modern online slot will have many millions of variations as to how the symbols can land on the reels. Each time you click spin, the RNG will select one of these variations at random and these result in the symbols you see on the reels.

Of course, some of these millions of variations are winners, a small number are the big jackpot prizes you can win. And it is all down to the machinations of the RNG on each spin that decides if you are a winner or not.

Now that we have explored some of the key concepts behind slot gaming which more experienced players take note of, you can now start to look at the slots you play in a slightly different way.

Good luck!

Byline: This article was published by Mega Moolah expert Henry. Media and other enquiries.

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