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Ask the Slot Expert: How Do "Guaranteed to Hit" Jackpots Work?

7 December 2011

By John Robison

There are casinos promising that someone will hit the jackpot before or by the minute a certain amount is reached.

Really? John, I thought all spins are random because the law requires so. By guaranteeing that the jackpot will be reached by a certain time or sum, isn't that somehow manipulating or controlling the RNG? How do they do it?

Thank and bless you for your continued clarifying of slot-machine issues.


Dear Peter,

Thanks for the kind words.

These "guaranteed to hit" jackpots are decided outside of the usual reel-spinning game. As you point it, it is illegal to not display the result selected by the RNG.

A system separate from the slot machines administers the jackpot. The system randomly chooses a trigger amount between the minimum and maximum levels chosen by the casino. As players play the machines that participate in the jackpot, a percentage of each bet is added to a running total maintained by the jackpot system. The player who pushes the running total equal to or greater than the trigger amount is the one who wins the jackpot. After the jackpot is won, the system chooses a new trigger amount, zeroes the running total, and the process starts over.

Best of luck in and out of the casinos,

Send your slot and video poker questions to John Robison, Slot Expert, at Because of the volume of mail I receive, I regret that I can't reply to every question.

John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots