Return-to-Player (RTP) & Variance in Casino Games

Together RTP and variance should be used to decide which casino games you will play. RTP will help you understand your chances of winning, while the variance gives you an idea of how often a casino game will payout.

What is RTP?

RTP in a casino is similar to the house edge, but it instead describes the percentage edge for the player. It is the acronym for the term ‘return to player’. Almost all slots have an RTP assigned, while some table games will show either the RTP or house edge.

In essence, we could switch the term ‘house edge’ and call it the ‘player edge’. The ‘player edge’ would then be the RTP of a game. For example, if a blackjack table has a ‘house edge’ of 0.5%, then the ‘player edge’ or ‘RTP’ would be 99.5%. Similarly, we could take the NetEnt Mega Joker online slot game that has an ‘RTP’ of 99% and switch this and say that the ‘house edge’ is 1%.

As an online casino player, you will see that nearly all video slot games will be designated an RTP. This is basically a way to guide slot players so they can judge how often an online slot game is likely to pay out on average.

How Is RTP Calculated?

The RTP is calculated in the same way as the house edge – there is actually no difference in the mathematic equation. Therefore, as with the blackjack example above, the 0.5% house edge can be easily converted to the 99.5% RTP figure. All house edge and RTP calculations are based on probability.

Most casino table games have already had their RTP calculated when the game was invented many years ago. These are games such as blackjack, roulette, baccarat, and so on. Although, occasionally, casinos will add an extra side bet or rule to make the game more interesting, and these changes will affect the RTP.

On the other hand, online slots rarely have the same RTP. This is because the reels, pay lines, features, payouts, and a number of symbols change so often. For the slot game developer to calculate the RTP, all these variables need to be considered, and a mathematical equation will determine the probability of each win.

What is Variance?

Variance is otherwise known as velocity. It basically tells us how frequently the casino game will pay out. It can also indicate how big the payouts are when you win. For instance, a high-variance slot will pay out less frequently compared to a low-variance slot game. At the same time, the high variance slot will payout a higher amount.

Most of the time, you will hear people speak about low, medium, and high-variance slot games, but in a casino, there are tons of games, and all of them have a certain variance. Games like craps and roulette have multiple bets, and each one can have its own variance.

An example of a low variance bet would be using outside bets that pay even money or 2 to 1 on a roulette table. Whereas playing inside bets are medium to high variance wagers.

Below we explain each one in more detail.

High Variance – High-Risk High Payout

These games rarely produce small wins. You could make several bets without a win, but if you remain persistent, when the game finally does payout, you will usually win big.

Roulette Example: If you make a straight bet playing roulette, then you are betting on a single number with a 2.70% chance of winning in exchange for a 35 to 1 payout. The chance of the win occurring is low, but when you do win, the reward is high.

Slots Example: For an online slot, it could be that you do not roll in many symbol combinations, and instead, you need to be patient and wait for the high paying feature to trigger, which could take some time to achieve.

Medium Variance – Medium Risk Medium Payout

These games give you a mix of smaller wins to keep your bankroll topped up and the gameplay interesting, but equally, there is a good chance of a big win rolling in at any time.

Roulette Example: Again, playing roulette, you can make a line bet covering six numbers, giving you a 16.2% chance of winnings and a 5-to-1 payout.

Slots Example: A slot game that is classed as medium variance has the potential to payout decent wins in the base game over time, and also, the feature bonuses can land with some regularity. Some medium variance slots can still have low-frequency payouts in the base game, but it is classed as a medium variance slot because it has two bonus games!

Low Variance – Low-Risk Low Payout

These games never really pay big prizes. You will find yourself winning little and often going on long winning streaks, but that does not mean every win will cover your stake. Instead, these games will cover a percentage of your bet regularly and in between, you will land wins that multiply the total value of your bet.

A low-variance game will payout often with low odds. This could be any game where the odds are 50/50 or close to 50/50.

Roulette Example: If you bet on red or black, you have a 48.60% chance of winnings, and you will be paid even odds on the bet.

Slots Example: Many of the 243 ways to win and Megaway online slots are low variance. Some of them will payout symbol combination wins regularly, and their free spins games will award a low number of free spins that are easy to trigger. This keeps the payouts coming, but the wins are not usually very high.

The Biggest Mistakes Players Make with RTP, Variance, and Variation

RTP is one of the most misunderstood concepts in casinos, followed by the terms ‘variance’ and ‘variation’, which often get confused.

When you look at a game with an RTP of 98%, for example, it may lead you to believe that for every €100 you bet, you will get €98 in return. However, this is not the case, and it would be pretty boring if it was the case because it means you would rarely have a winning session or profit. RTP is based on probability, and so it represents an estimate of how much you are predicted to win over an undefined period of time playing a game according to probability.


Variation is basically your upswings and downswings, or you may have heard players call it 'running hot' or 'running cold'. RTP is your long-running expected return to the player over time. You should never think that RTP will pay back according to how you bet, i.e., you will never be able to consistently bet €100 and get €98 back because variation will affect it.

Here are some examples of how variation affects probability:

Heads or Tails: We all know the old game of heads or tails. The RTP for winning a game of heads or tails is 50%. This never changes because it is based on mathematical probability. However, probability is not constant. You could end up betting on 'tails' and lose 40 times out of 50 flips. However, over the next 100 flips, you could win 85 'tails' bets. Every game of chance has variations in its

Dice: You can apply the same tests to a game of dice. In theory, probability suggests that you should roll high/low or odd/even 50% of the time. Or you should roll a 6 at least 16.67% (1 in 6 rolls), yet we could roll the dice 20 times and never see a 6.

Roulette: Now you can apply the same theories to French roulette, in which you may continuously bet on zero, which has a 37 to 1 (2.7% RTP) chance of spinning in on the wheel, yet you can go 100 spins without a zero result, and then suddenly the next two coups produce a zero.

Player Flaws

A good example of a player flaw is blackjack. Most Blackjack tables have an RTP of 99.5%, but this mathematical equation assumes you are playing basic strategy. If you are not, then you give the house back anything up to 5%, and very bad players can end up giving back 20% RTP or more by making the wrong move, like splitting 10s when you already have a perfectly good hand worth 20. In addition to this, if you play the Blackjack side bets, then you are further reducing your RTP.

Online Slots Variation

Slots are a little different from roulette. We don't really have the probability of heads/tails, dice, or roulette to set a baseline. Neither do we have the mathematical equations or charts used for blackjack's basic strategy. Slots are totally random, and as such big wins will ride entirely on luck.

Every slot uses an RNG (Random Generator) that runs several thousand-reel combinations through it every millisecond. When you press the button, it stops on one of these combinations. The reels themselves only spin for a show just to make the game more fun, but the result was already decided when you pressed spin. Finally, the reels will stop spinning, producing the combination you randomly selected when you pressed the spin button.

Both online slots and land-based slots behave in the same way. Therefore, the point of RTP for slot games is to give you a rough estimate of your long-term return by playing that slot.


RTP is used to indicate how much a casino game will pay out over time. On the other hand, ‘variance’ is used to tell you often a casino game should pay, plus it can also be an indicator of how much the game pays out. Always remember that RTP is just an indicator of what you are predicted to win in the long run and, according to probability, which variation will affect the amounts you win and when you win them.


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