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Volatility in Slot Machines

Volatility in Slot Machines

Last updated: 17 November 2023.
Author: Bohdan Lytvyn

Today we are going to talk about volatility, so you may have heard someone say this slot has potential or this slot is volatile and you might have wondered what that means. And why should you care about volatility, and how can you tell how volatile a slot really is?

Definition of volatility in slots

Let us start with a simple set of definitions: if a slot has high volatility, the chances are that it has the potential for some really big wins. A really big win might pay 200 or 1000 times your spin bet, or maybe even more. Of course, such spins are really rare and on a high volatility slot, the vast majority of your spins will be duds. A lot of their bonus games might also be duds too.  On the other hand, if the slot has low volatility, the most you're likely to win on a single spin might be only 50 to 100 times your spin bet, but these same online slots usually give you more of these winning spins, even though they are generally only modest.

Think of it in another way (anecdote): Volatile slot means that you might win with luck. High volatility means: you aren't winning unless you have a horseshoe with you that helps.


But why exactly do we say that a volatile slot has a potential to pay big?

It is so because with highly or extremely volatile slots, a big portion of RTP (Return to Player) is given to big or very big winnings. Whereas, the small or medium winnings will come less often. 

Volatility Formula

In case now for the mathematicians out there, you might be hoping to see some kind of formula. Here it is, you might recognize it as two times the standard deviation or the standard deviation, with 95 % confidence slot designer is called this.

Relations of Volatility to other key concepts

  1. How does the Volatility relate to RTP?
  2. How does Volatility relate to Hit Frequency?

As noted above, Volatility is what portion of RTP is given to big winnings. The RTP, in turn, is how much you may statistically expect to win back of your money wagered as per each bet (given as a percentage, for example 95%). So, if you’d receive your winnings in big amounts, but more rare, then the volatility is high. If otherwise, it’s low.

Hit Frequency (given as a percentage, for example 18%) is how often you may statistically expect to land any winning. Obviously, Volatility is inversely proportional to the Hit Frequency: the higher Volatility of a game, the lower its Hit Frequency. Importantly, Hit Frequency is good predictor of the Volatility Index. 

Related article: 

How casino games work? Basic concepts and 

RTP in casino games: how it works.

What is the Slot Volatility Index?

The volatility index or VI for short is an internal measure of slot game volatility (used by game developers). It works like this:

  1. if a slot has a VI of about 5, it might be considered low volatility;
  2. if a slot has a VI of above 15, it might be considered high volatility.

But, unfortunately, slot players never get to see the Volatility index. It's an insider secret, so let's shine a little light on the subject to give you a feel for things: let's take a look at how one might experience a low volatility machine and a high volatility machine.

How does the volatility of slots translate in gaming experience? 

Here is the experiment. We made 10 sessions of 500 spins on low and high volatility slots to see how the player budget will be exhausted during the playing sessions. 

Low volatility slots

Let me first show you a low volatility slot machine by starting with €100 and betting €1.00 per spin for a session of up to 500 spins. For most players, 500 spins is about 30 to 40 minutes of play. I am going to show 10 sessions of 500 spins to give you a sample of how things might go, but keep in mind that even ten sessions won't tell you the whole story. So here we go. We are playing a penny machine with 85 % pay back, which is a type machine. The money in your bankroll is shown along here, and this shows the spins one through 500. Each coloured line represents your money going up and down during that particular session.
Huge wins are not possible on this machine, but modest wins do happen somewhat frequently, notice that our €100 lasted 500 spins 7 out of 10 sessions. Nothing dramatic happened, but we did come out a little in two of the sessions, not bad at all. After 500 spins on a type machine, all in all, we got a fair amount of play on this low volatility slot machine, but maybe you find these low volatility slots boring. 

return on low volatility slot with €100 balance and 4 hours playtime

High volatility slots

So now, let's take a look at the high volatility slot machine. This slot machine has the potential for some really big wins in this case, wins can be more than say 250 times your spin bet. Of course, such wins are going to be rather rare and most of the spins are going to be duds or small wins. As a result, we run out of our money most of the time fairly quickly. Ah, but in two of these sessions we made some dramatic wins, and this is why some players like these slots because they've got the potential and they are willing to take the risk of busting more often to get their lucky slot.

return on a high volatility slot with €100 balance and 1 hour playtime

Related article: Online slot games crash course

Who plays High Volatility Slots?

Gambling companies call these folks that like high volatility Core Players, because high volatility machines tend to drain your bankroll faster, unless you know any better how to skip such machines that are set really tight. Only dedicated core players will try to stick it out long enough for that really big win. And, guess what? A particular high volatility game might actually be set looser than a low volatility game sitting nearby. It is usually difficult to tell unless you play these machines long enough and to prove a point which of these two machines is tighter, the low volatility machine or the high volatility machine.

With a low volatility slot you get more frequent wins, but the bigger wins tend to be modest. So, your money tends to slowly disappear unless you’re lucky.

The answer is that the RTP or Payback of both of these machines are identical. Their RTP both 85 % the same, in fact as the previous two charts volatility might also help to explain why some players accuse casinos of changing the payback percentage on their favourite machine. The payback percentage, probably didn't change volatility just makes it look that way. 

Question: does any of this matter if you're just playing for a few hours?

Answer:  High Volatility can make a slot feel really tight and you can get long periods of low pay or dud spins...with a rare big win spin once in a while. So, if you play for a few hours you might experience a dry spell and money dries up...unless you get lucky. 

Is there a way to think of playing slots like investing in a stock market?

I think you may lawfully look at these games like playing the stock market... such as investing in Blue Chip companies versus the higher volatility newer stock.  "With risk comes rewards" doesn't always work, but when it does, it can definitely be rewarding!

How to determine a Volatility Index?

How might you be able to tell well here are some clues.

Branded slots are rarely volatile

First, if the slot machine features a famous name like a movie TV show, a singer brand, etc, there is a good chance that the game is low to moderate volatility. These games are usually designed more for entertainment than for gambling and for big wins, and if the game makes a big deal out of a win, that's just five times your spin bet that's a pretty good clue that it's a low volatility game. Sometimes you might see these slots refer to as branded or premium slots. That's kind of an industry term.

If a game’s symbols pay x200 or more in base game, it’s likely to be volatile

Second, take a look at the game's rules: if there is the potential for huge wins of, let's say 200 times your bet for the base game, there's a good chance that this game has higher volatility. It might take a little calculation to see if the potential for huge wins is actually there, but look closely at games with many paylines or “ways to win”, among other things. For example, these are games which have 243 or 1024 or even 4096 ways to win. Many of these have stacked symbols that can show up multiple times on the same reel. Thus, your win can grow exponentially with good winnings to the game.

Choice of volatility in a bonus game is a way to control your risk exposure

Third, some games feature bonus games that give you a choice of volatility. The most common is the bonus that trades off the number of spins against the size of multipliers. Variations include trading off the number of spins against the number of added wilds or the level of the stack symbol.

There are also bonus games that trade off the number of spins against the number of pay lines in all of these cases, the choice that gives you the most spins is the lowest volatility. There is one exception. This is the mystery choice that randomly chooses the number of spins and the choice of multipliers, wilds or paylines, etc. Most of the time, the mystery choice will give you a combination that is probably worse than one of the standard choices, but once in a while, it will give you something really lucky and you got a lot of spins and a lot of multipliers, wilds or paylines, etc 

Don't count the progressive prizes into actual volatility

And a fourth point. Don't count the progressive prizes when looking at the potential for huge wins in a slot game. The progressive bonuses are usually a separate game from the main slot game and progressive games are usually high volatility and with tighter payback percentages than the regular games. Those huge progressive jackpots are there to try to attract you to play that game. Much like a bait, it is designed to attract players. 

Related article: A list of best high volatility slots

Do slot providers indicate volatility (correctly)?

Only a few slot companies indicate the volatility as some of their games on their website or game product sheets. For example, you may check out ELKKonami or AGS for how they tell you. Also, a small number of casinos have tried indicating to players which machines are high or low volatility. They might sometimes say something like more wins on the low volatility games and bigger wins on the high volatility games. 

Well, I hope you now have a little bit better understanding of what volatility is and how to spot it and how it affects the way that you play slot machines. 

Now, if you have any questions, please write them down to my ny email:[email protected] and I'll try to respond and good luck out there in the casinos.


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