Guide to variance

The Maths Of Winning

What makes you a winner? Is it Lady Luck, bestowing her blessings on you? Or is it random chance in the chaos? Both are appealing theories, to be sure, but the reality is based a lot more on science than on fantasy. It all comes down to mathematics.

Does that mean you need to be a mathematical genius to play the wide variety of slots available in online casinos? Not at all! A basic understanding is more than enough to help you figure out which online slots will yield the kinds of results you’re after. 

Of course, it’s worth remembering that there is always an element of randomness built in, and even an in-depth understanding of variance won’t guarantee you a win when you expect it. However, this guide will give you a good understanding of how it works and how to use it to your best advantage.

A casino is a casino is a casino, right? How different can one casino be from another? All they do is exchange money for chips, offer games, and then exchange chips for money.

Well, no. No story goes, “Once upon a time, everything was simple, everything was the same, and everyone was happy. The end.”

Every casino – both brick and mortar and online – is unique. Yes, there are similarities, both legislative and game based, but there’s no way to summarise all casinos with just a few simple sentences.

Luckily for you, we have taken the time and effort to really get into the foundations of online gambling: what makes it tick, how it works, what players can expect, and so much more. Here, we offer you all the in-depth guides to online casinos and gambling you’ll need. And we take that promise seriously, which is why we are constantly working to add more guides that cover every aspect of the online casino experience.

In this series of guides, you will find information about jackpots, variance and volatility, online casinos, casino bonuses, withdrawals and deposits, and more.

Why should you use guides?

Casino guides like these can really help enhance your online casino experience. For example, jackpot guides don’t just tell you what a jackpot is; they explain the various types of jackpot, how they work, how to play to win, where to find games with different jackpots, and even who the game developers are.

Casino bonus guides are another super useful way to figure out which online casinos will work best for you. We don’t only look at the types of bonus offered, but explain how they work, the hidden pitfalls to look out for, and ways to make the most of your wagering requirements.

You’ll find enough information here to keep you busy longer than a great game of poker, so dig in, and come out the other side a little more knowledgeable. And if there’s anything you’d like to learn more about that you don’t find here on CasinoPlay, let us know. Happy reading!

To fully understand variance, we need to take a look at a couple of other concepts within the online casino space. Some of the terms used here are also discussed in much more detail in other segments on this website.

The RTP percentage is the amount of money that the game pays out, compared to how much is put into it. For example, if a slots game has an RTP of 96%, that means it pays out, on average, 96% of the total bets played over time.

The house edge is the reverse of the RTP. In other words, it is the percentage of total bets placed that the house, or casino, keeps. For the slots game mentioned in the previous example, the house edge would be 4%.

Volatility refers to how frequently and how much players can expect to win during a game session. Low volatility equals more frequent smaller wins, while high volatility equals fewer bigger wins. Learn more about the complexities of volatility here.

Variance is very closely linked to the volatility of a game. While the RTP shows you what the aggregate percentage of payouts are in the long run, this is across the whole game and all players over time.

Variance, however, gives you an idea of how likely you are to win during any given game session, and whether those wins will be bigger or smaller.

Many players consider variance and volatility to be the same thing. However, while they may be very closely linked, they’re not quite the same. Volatility refers to the game’s built-in algorithm that determines frequency and size of payouts over a specific period of time. Variance, on the other hand, is a statistical model that shows how likely you are to deviate from the RTP.

Variance, in other words, is just how far your cumulative wins or losses can potentially deviate from the RTP. If a game has low variance, you can take its RTP as a pretty accurate indication of how your game session will run, regardless of how long you play for. However, if a game has a high variance, you could expect your session to vary up or down from the RTP by a significant margin.


The risk-reward ratio of any given game can be equated to its variance. A game with low variance will have a low risk level but will also have a low reward level. On the other end of the spectrum, high variance means you could potentially win bigger prizes, but you also stand to lose more often.

To find out what a particular game’s variance is, you can look at reviews and game guides, as some will mention the variance. However, this information isn’t always easily available, so it helps to know how to evaluate a game to figure out its variance level. In the following segments, we break down high, medium and low variance and their indicators.

What it is

High variance is the type of game that risk-takers love. Your risks are higher, because the game pays out a lot less frequently, but the potential wins are on the high end. With these games, you could potentially win very big, very quickly, but you could also play several sessions over the course of several days and win nothing. In these games, you may deviate quite a lot from the RTP during a given play session.

How to spot it

The easiest way to figure out if a game is high variance or not is to look at the pay tables. Compare the maximum bet amount to the maximum payout amount. If the maximum payout is around 50 times the maximum bet amount, this is a good indicator that the game has a high variance.

What to expect

If playing a game with high variance, you can expect to bet big, play fast and possibly lose big, too. On the other hand, you could play just a few spins and win a considerable jackpot. This is the type of game to play if you have a bit of cash to burn, and are looking for the excitement that comes with a risky, but potentially rewarding game.

What it is

Most online casino slot games fall into the medium variance category. That means you can expect moderate bet amounts and good payouts. Wins will be more frequent than in high variance games and fewer than low variance games. The deviation from the game’s RTP, for both wins and losses, is not huge, but it is present and notable.

How to spot it

Medium variance games tend to have some of the more enjoyable features of online slot games, like free spins, multiple paylines and bonuses. The maximum bet amount is mid range, and the maximum payout amount is around 30-40x that maximum bet.

What to expect

This is a great way to play slots if you want a balance of play time and excitement. The risk-reward ratio is enough to provide the thrills, but the game is designed to allow your bankroll to last longer. You can also expect a reasonable balance of small and bigger wins.

What it is

This is the ultimate in low-risk game play. Your rewards are significantly lower than in a high variance game, but the payouts are far more frequent. These games are unlikely to net you a mega-millions jackpot, but they will provide consistent returns that come pretty close to the RTP of the game.

How to spot it

Low-variance games usually have low betting amounts and only have one payline, although this isn’t a hard and fast rule. You will notice plenty of regular, small wins, and the maximum payout will be around 10-20x the maximum bet.

What to expect

Even a serious high-roller can appreciate the appeal of a long, lazy game session, where the wins and losses even out, and it’s more about the experience. These are the low-risk, low-reward, playing-for-the-fun-of-it games, where your bankroll lasts longer, and you may even walk away with a small profit.

It can take time and experience to figure out a game’s variance, as well as its volatility for yourself. Because it forms part of the game’s algorithm, this is information that isn’t disclosed by the designers.

The best way to quickly find out a game’s variance, according to those who have played and experienced them, is to check out some reviews. Check out CasinoPlay reviews here.

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