How Are Slot Machine Paybacks Verified?

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Cash being inserted into a slot machine

When a slot machine is said to pay back, say, 90 percent, how is this verified? That’s what today’s question covers:

In the RNG post you mentioned examples of 90% payback one 88% payback that the machine meets. Is this audited by a third party to validate this is happening? Or does each casino audit themselves?  Just wondered about this.


Great question! A slot machine’s payback is audited in multiple ways, and often involves third parties.

At the beginning, when a game is seeking approval for various casino markets in the United States, they go through third-party lab testing to certify that what the game is said to offer in payouts is matched by actual game play. The core lab companies include GLI and BMM Test Labs.

The labs test to make sure that the games meet the regulations of a market they’re going into, along with confirming the payback expectation meets reality. This gives gaming regulators confidence in the game.

Casinos are also required to verify games are working out as expected. This reporting will be done internally, but also shared with third-party companies who collect data for reporting, casino gaming commissions and the game makers themselves. 

On occasion, casinos will spot unexpected or unusual trends for a game, and it could be a sign of an issue that the game maker needs to address, so the game’s actual performance is also monitored by a variety of sources.

In states where minimum payback requirements exist, casinos will have to be able to prove that those regulations are met, both in configuration and actual payouts over the long term. Casinos can and sometimes will remove machines that deviate too wildly from the norm. Some casinos won’t even install games that are too volatile if they would rather have games more reliably showing up in a certain range.

So the answer to your question is yes, casinos will internally verify machines are paying what they should, but a lot of external eyes and ears are on that data as well. In the end, everyone wants to ensure that the game is doing what it should, because it ensures fairness for the player, piece of mind for the casinos buying these games, and trust for the game makers who offer them.

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2 Replies to “How Are Slot Machine Paybacks Verified?”

  • Joyce Huget says:

    can you have a list of on line casino that we should not go too or what we can do to look into a casino Im one that reads the rule

    • says:

      Hi Joyce – the sites we recommend are listed here on Flip The Switch. Any other sites not listed here we have not reviewed. There are a lot of ways to research sites, such as third-party reviews, the Better Business Bureau, etc., but the primary thing we recommend is to find a list of sites that are legal in your area.

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