How Casinos Gain Their Edge in Slots

All gambling games are designed to give the casino an advantage, known as the house edge, and slots are not an exception to this rule. Yet, these constantly buzzing machines are unlike any other casino game. Card or dice players can easily calculate their odds and know exactly what they are up against but this is not the case with real spinners.

The mathematics behind slots is rather complex due to the incredibly high number of possible outcomes and combinations. On top of this, casinos prefer to keep all the parameters that go into the calculation of their slots’ odds a secret.

Despite these obstacles, a serious reel spinner always seeks to understand how the house edge works and how to calculate it. This gives them an insight as to which machines to play and which ones to avoid. This article explains how the house obtains an edge in slots, how to calculate it, and how to spot the games that can give you positive expected value.

Why There Is No Need for the House to Cheat Slot Players

1They already hold an advantage

Many gamblers who experience devastating short-term losses are quick to assume casinos resort to deceptive methods like rigging the slot machines. The fact of the matter is such players are simply bitter and cannot handle losses that usually result from a lack of understanding of the games, bad luck, and inadequate strategy.

In reality, there is no reason for casinos to cheat players through underhanded means. Gambling establishments already hold an advantage over their customers. This advantage is inherently built into the structure and payouts of casino games and is known as the house edge.

It results either from poor playing conditions, i.e. from disadvantageous rules, or from reductions in the payouts as winners are never paid at true odds. Often the house edge comes as a combination of both factors.

2The house always win

It is not unheard of for slot players to suffer huge losses or walk away thousands of credits richer from the casino floor. Everything is possible in the short term after a dozen spins. But the sad truth is most reel spinners will inevitably lose over the long run. This is so because the machines have been programmed to return less money than gamblers collectively wager over hundreds of thousands of rounds.

This pre-programming is perfectly legal mind you. The house is allowed to retain specific percentages from its games by its local gambling regulators. The house edge ensures the casino turns sufficient long-term returns that enable it to run its operations and collect a guaranteed profit.

3Regulations and legalities

Another equally compelling argument against casino cheating has to do with regulations and legalities. Licensing authorities are quick to react to cheating allegations. If foul play is indeed at hand, the cheating operator is heavily fined or has its license revoked.

The bottom line is slot players can have their peace of mind as long as they are gambling with licensed and properly overseen operators. It makes no sense for trusted casinos to put their reputation and licenses at stake when their built-in advantage already enables them to generate consistent long-term profits.

The House Edge

Figuring Out the House Edge in Slots
There is No Way To Reduce the House Edge in Slots

The Hourly Expected Losses of a Slot Player

1How to calculate the cost

Knowing the theoretical return and the house edge of slots cannot help you devise a winning strategy to beat the game. With that in mind, this information is particularly useful when it comes to choosing what slots you play because the higher the house edge is, the faster you will lose money.

The advantage is in favor of the house which ultimately means players end up losing money in the long run. However, the knowledge of the house edge allows you to calculate the cost of playing slots for entertainment.

2Factors you need to consider

Several factors are taken into consideration for these calculations. Apart from the house edge, you must take into account the average size of your bets and the average number of spins you play per hour. The number of spins depends on your style of play but there is a general consensus that most players make between 400 and 600 spins per hour.


Let’s assume you play Microgaming’s Game of Thrones 243 Ways slot with a house edge of 4.90%. You prefer a more dynamic pace so you go through 600 spins each hour. Your average bet per spin is $1.20.

You can calculate the long-term losses you are expected to incur per hour by multiplying all of the above-mentioned factors like this 0.049 x 600 x 1.20, which corresponds to long-term hourly losses of $35.28.

You need to have enough hours under your belt to arrive at these numbers, though. Both the theoretical return percentage and the house edge are meant to represent long-term expectation. The more rounds you play, the closer you get to your average hourly expectation, which is negative for slot players as we shall explain later.

Casino Myths and Tricks

Can Casinos Manipulate the Odds to Increase Their Edge?
Casino Tricks to Boost Slot Profits

Slots and Positive Expected Value

All casino games, including slots, are based on mathematics, which makes it possible for players to calculate how much a given bet is worth. Players face two options on the casino floor – they can either play a game with positive expected value or one with a negative expected value. The term expected value, or EV, refers to the average amount a given bet is worth. Let's see how slots perform in terms of EV.

Defining Positive Expected Value
What Slots Offer Positive Expectation to the Player and When
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