Slot Machine House Edge (Odds Explained for 2026)

When I started gambling, I needed slot machine house edge and odds explained to me. That was many years ago, but I still hear people asking about slots returns, the house edge, and odds. So I put together a complete guide for easy reference.

Once you learn how to determine the house edge and odds from the return to player percentage, you can quickly figure out your expected return, just like you can with the lottery. And with this information, you can quickly compare two or more slots games.

You’re getting ready to learn everything you need to know about slot machines house edge and odds. And with this information, you never have to play on a bad slot machine again.

Slot Machine House Edge Explained

Slot machine house edge, displayed as a percentage, tells you how much the casino makes from the machine. The higher the house edge, the more the casino makes. And the more the casino makes, the more you lose.

You can’t determine the house edge for a slot machine by looking at the machine. But some slot machine makers publish the return to player percentage for their games. The return percentage, also called RTP, shows the expected return as a percentage.

Here’s an example:

If a slot machine shows an RTP of 94%, it means the programming returns 94% of all wagers made on the machine. So, if you take 435 spins at $1 on each spin, you bet a total of $435.

You can multiply the RTP times your total amount wagered to determine the expected return. $435 X 94% = $408.90.

You lose $26.10, determined by subtracting the return of $408.90 from what you bet, $435.

But that’s a long term average based on the odds of hitting the various winning combinations on the pay table. Your results in any given hour will differ widely, usually. That’s why people play slot machines to begin with.

When you know the RTP, you can quickly determine the house edge. Subtract the RTP from 100% and it gives you the house edge.

100% – 94% = 6% house edge.

When you know the house edge, you can multiply it times the amount bet to determine your expected loss.

6% X $435 = $26.10

When comparing slot machines, the best slot machine to play will always be the game with the lowest house edge. Or looking at it using RTP, you want the machine with the highest RTP.

The Only Time a Higher House Edge Is Better in Slots

It might sound odd after learning about slot machine house edge, but in one situation, you’re better off playing a slots game with a higher house edge:

If you have to choose between two slot machines and one machine has a higher house edge but lower cost per spin, sometimes you’re better off playing on the machine with a higher house edge.

Here’s an example:

One slot machine has a house edge of 4% and costs $2 per spin. The other machine has a 6% house edge, but only costs $1 per spin.

You’re going to play 1,000 spins and need to choose the best machine. Determining your expected loss shows you the best option.

You can expect to lose $60 playing the machine with a 6% edge. And you can expect to lose $80 playing the machine with a 4% edge.

Truthfully, this situation doesn’t present itself often. Usually, you can find a slot machine with a lower cost per spin with a comparable house edge to another machine with a higher cost per spin.

Sometimes dollar slots are better than penny slots, but not always.

Slots Games Odds Explained

Slots games odds aren’t as straightforward as the house edge and RTP. And when some gamblers talk about slot machine odds, what they use are either RTP numbers or house edge numbers.

If you know the RTP and house edge for a slot machine, you don’t need to know about the odds.

But I’m going to explain slot machine odds in this section.

Odds are usually used in a way that tries to explain the chance of something happening. If you have a shuffled deck of cards, what are the odds of the top card being a club?

You know that 25% of the deck, or a quarter of the deck, are clubs. As odds, this can be displayed as one out of four or three to one.

One out of four means there are four suits with an equal number of cards, and clubs are one of the suits. Three to one means three suits aren’t clubs and one suit that are clubs. And because the same odds can be displayed in two different ways, it can be confusing.

Here are two important questions:

How do odds work with slot machines? And how can odds be helpful when playing slots games?

The Best Way to Use Slot Machine Odds

The best way to use odds on slot machines involves the symbols on each reel. You can watch each reel and record every symbol. Once you map each reel you can determine the odds of each symbol landing in each space.

Then you can determine the odds of symbols lining up to produce winning combinations and pay lines. This is just a matter of clocking how often each symbol turns up as you’re playing, but you need a large sample size to have any sense of accuracy. Not all the symbols have an equal probability of showing up on a reel.

However, using slot machines odds this way doesn’t help. If you know the RTP and house edge, you have more useful information than determining odds.

Usually, the slot machines with the best odds are $1 and $5 machines.

And the machines with the worst odds are gas station slots.

How Slot Machines Work

In the last section, I explained how you can record the symbols on reels to determine odds. And everything I explained was true with slot machines using real reels. But modern slot machines use video monitors and computer programming.

While a video slot machine can use a set pattern for each reel, they don’t have to use a set pattern.

Here’s how most slot machines work in 2022:

I’ve simplified this a little so you can easily understand it. But it explains why tracking the position and symbols on the reels doesn’t help much.

The programming on the slot machine determines if you win or not as soon as you hit spin. And if you win, the program determines how much you win.

After this, the program directs the display or monitor to show the result using reels, rows, and symbols. And this all happens based on the house edge programmed into the slot machine.

I hope you see why this negates determining odds based on reels and symbol position. The programming can display symbols and reels in any pattern it needs to display the results the program already determined.

Slot machines in land-based casinos and virtual casinos, both mobile and online, work basically the same way.

For a deeper dive into how slots work, John M Pacyniak wrote a paper titled A Personal Guide to Electronic Slot Machines that’s worth reading.

Slot Machine Strategy

With everything you’ve learned about slot machine house edge and odds, the next question you might want to ask is, can you use this information to use strategy when you play?

I don’t know if you can count this as a strategy, but the best slot machine strategy will always be playing on machines with the lowest house edge.

You can’t develop a strategy that helps you alter the outcome of a slot machine. Because the outcome of each spin gets instantly determined when you push spin, you can’t use strategy to change anything. And because the house edge is strictly controlled by the programming, the long-term returns for each slots game are locked.

Using Math and House Edge with Slot Machine Bonuses

I love using math when comparing slot machine bonuses. And when you know the house edge for any slots game, you can quickly see how much a bonus can help you. The best ways to show you how to run the numbers for a bonus are a few examples.

Here are two examples:

In the first example, you’re playing a slot machine with a 95% return to player percentage. This means the house edge calculates to 5%.

You receive a bonus of $1,000 on a deposit of $1,000. You have to wager the deposit and bonus amount 40 times to clear the bonus.

Determine the amount you must wager by multiplying the total amount of the deposit and bonus, $2,000, times 40. In this example, you have to wager $80,000.

Next, multiply the total amount you must wager, $80,000, times the house edge of 5%. This calculation gives you the expected loss.

$80,000 X 5% = $4,000 expected loss.

The numbers show you’re expected to lose all of the bonus and your deposit before clearing the bonus. Most slot machine bonuses work this way.

In the second example, you receive a 200% bonus on a $500 deposit. You deposit $500 and receive a bonus of $1,000, for a total bankroll of $1,500.

You have to wager the bonus amount 25 times to clear the bonus. And you’re playing on a slot machine with a 96% return to player percentage.

With a house edge of 4%, you multiply the amount you must risk, $25,000, times 4%. Your expected loss comes to $1,000.

In this example, the expected loss equals the bonus amount. So on average, you should have your $500 deposit left when you clear the bonus.

Conclusion

You can quickly determine the house edge for any slot machine if you know the RTP. Of course, you can’t always find the RTP. But many online slot machine creators release RTP numbers.

I don’t recommend playing slot machines if you don’t know the house edge. And you should always play the slots games offering the lowest house edge.

You can use slot machine odds, but the house edge provides more actionable information. Start building a list of slot machines with the lowest house edges so you always know which machines to play.