If you put a coin into a slot machine, how much money should you expect to get back? For most players, this is a mystery: the payouts are random, and jackpots are rare, making it hard to tell if you’ve been in a bad streak or a machine is just a poor bet during a losing streak.
However, there is some finely honed math working behind the scenes to drive the prizes that are awarded to players. Return to player, or RTP, is a measure of just how much of the money that goes in will eventually be returned to gamblers, and can be a useful tool in helping you determine which games you’d like to play.
What is RTP?
Return to player is a figure, usually presented as a percentage, that describes how much of each bet put into a slot machine that will be returned to players over the long run. For instance, a machine with an RTP of 95% is expected to return $95 out of every $100 put in over the course of its lifetime.
Of course, that doesn’t mean that every player will get exactly 95% of their money back: that would not only be too simple, players would quickly get tired of seeing their money (slowly) disappear. Instead, this is a projection of what is expected to happen over the long run: over years and years of play, including any jackpots that might be awarded. Any given player could do much better or worse than that figure, even if they were to play for thousands of spins.
How RTP is Calculated
Return to player can be calculated in two ways. Most simply, a casino might report how much has actually been paid out on a single title, or on their slots as a whole, over a given time period: say, a month or a year. This isn’t guaranteed to accurately reflect what will happen over the long run, but given a large enough sample size, it will probably be very close to the actual figure.
When it comes to setting the return on a given game, that is done by determining how often certain symbols will be hit on each reel. By knowing the probability of making all of the different winning combinations on the machine, and how much they pay out, the manufacturer can do some relatively simple math to set whatever returns they like, with many modern slots allowing operators to vary between multiple settings depending on how “loose” or “tight” they want their games to be.
Some slot developers such as US powerhouse IGT actually publish the RTP %s of all their slots. These are available in the par sheets which can be Googled online.
The presence of a progressive jackpot will change the payout percentage, often in ways that are good for the player. In these games, there is a base RTP, plus a modifier based on the size of the jackpot. For instance, a game may be designed to return just 85%, but the jackpot may add 1% to that for every $100,000 in the pool.
This is why progressive slots can sometimes be a profitable play for gamblers. In the above scenario, imagine the jackpot reaching $2 million. That would make the overall return to player 105% -- meaning players would actually have a 5 percent advantage each time they played! Of course, most players still won’t win the jackpot, but as a group, the players who go for it will actually make more money than they put in once the payouts are over 100%.
The mathematical principles behind return to player can be a bit confusing, and that has led to some major misconceptions about how slots work. Perhaps the biggest one is that a game will adjust its payouts in order to get closer to the percentage it is supposed to pay out: if it has been well below the intended prizes, it will give out more to compensate, while a machine that has been giving out a lot of prizes will go cold.
This is not the case. Operators do not need to change anything to get close to their theoretical RTP; they just need to rely on the same odds they always do, which over the long run, will pull their numbers close to where they were intended to be. Over time, a game will rarely (if ever) hit exactly its stated return, but the more it is played, the closer the percentage will get to that number, simply because of the laws of probability.
A similar misconception has to do with jackpot payouts. Many players believe that a top prize that has not hit in a long time will be due to hit: after all, now that the progressive jackpot has gotten so large, the game must be about ready to pay it out. In reality, every spin has the same chance of generating a jackpot. Because these prizes are awarded so rarely, however, there can be huge variations in the length of time between payouts: sometimes players will be pretty lucky and hit them close together, where at other times, nobody will find the winning combination for far longer than anyone anticipated.