Actual Slot Machine Return Percentages in Las Vegas

Last update: February 13, 2003

The following table ranks the Las Vegas casinos according to the looseness of their video display reeled nickel slot machines. The returns are based on a sampling of five different types of machines. The data collected goes back as far as October 2001 so the information is a bit dated.

Excluded Casinos

The Suncoast and Rampart Casino in Summerlin do not allow playing slots and taking notes at the same time. I can not include any casino that prohibits the method in which I gather data.

Location Averages

The next table shows the average return by location.

The above sign can be found across the street from the Palms. Although I did the study Anthony Curtis published it in the Las Vegas Advisor, which is how it become well known. The "..." in the sign encompases quite a bit of information, which was conveniently left off the sign. Actually the study only says that the Palms had the lowest nickel video slots of the casinos surveyed in Las Vegas. The small print at the bottom says, "Independent study conducted between November 2001-February 2002 on Austin Powers, Fortune Cookie, Reel 'em In, and Wheel of Fortune games. They left off Leopard Spots, and the study began in October.

Observations

There seemed to be no truth behind slot placement myths. Machines on the end of a bank did no better on average than those in the middle. There was also no correlation between return and proximity to such things as the main door, table game pit, high traffic areas, and low traffic areas.

Most casinos were very consistent in their slot returns. If one nickel machine had a return of x% then all others like it also returned x%. However some casinos did mix up loose and tight machines, most notably Treasure Island and the California casinos.

Methodology

A kind and anonymous source provided me with PAR sheets for the games in question. The EPROM (Erasable Programmable Read Only Memory) chip is what tells the machine the order of the symbols on the reel, in some cases how the stops are weighted, how much each winning combination pays, and any other pertinent information about how much the machine pays. It is up to the slot manager to select which EPROM chip to order according to the return percentage desired. On a typical game there might be about 8 different possible return percentages, ranging from about 85% to 98%.

Each of the different PAR sheets has five sets of distinct reels. On video display slots the stops are not weighted; in other words all stops are equally likely. The distribution of each symbol on each reel is what determines the theoretical return of the machine. For example a higher paying machine may have more of the higher paying symbols.

On the machine itself three consecutive symbols are visible on five different reels. By comparing actual observations of results to the PAR sheets it is possible to determine which reels the machine uses, and thus which PAR sheet and which return. There are various three-symbol combinations that appear in at least one but not all PAR sheets. So if one of these combinations occurs on an actual machine it narrows down the possible PAR sheets. By playing enough the player can narrow down the possible PAR sheets to just one.

To help identify the unique combinations I wrote a computer program for each game, which had the exact reel order of all 5 reels of all the PAR sheets. The program then counted the number of PAR sheets with each possible three-symbol combination. If the number was greater than 0 and less than the maximum then that combination was identified along with the associated PAR sheets it belonged to.

It is then a matter of simply playing the game and comparing the outcomes to the list of partially unique combinations. It only takes about 5-10 plays per machine to narrow down the possibilities to just one PAR sheet.

The averages in the table are actually an average of averages. For each kind of machine at each casino I took an average return. Then I took the average of these averages over the five kinds of machines I tested for.

"Slot Machine" Definition

There is some confusion about what constitutes a "slot machine" or "slot." My definition, and that of most gamblers, is a gambling machine with either actual spinning reels or video representations of the them.

People in the gaming business and regulators generally refer to a slot machine as any gambling machine, including reeled slots, video poker, video keno, video blackjack, etc.. For purposes of statistics both casino managers and regulators combine all the electronic gambling machines together. For example, reports such as the one by the state of Nevada and the Slot Chart in Casino Player magazine do not isolate just reeled slots but consider all electronic games a "slot." Therefore my return percentages should not be expected to agree with those reported by the casinos or regulators. As far as I know mine is the only source to isolate just the return of reeled slots.

Acknowledgements

I would like to thank Rob Feldheim for helping with the slot play and record keeping. Rob helped me with most of the casinos on the east side of town and part of downtown. I would also like to thank Par Sheet Pete (not his real name) for providing the par sheets, without which this project would not have been possible.

Articles

The main-stream media has covered this study in depth. Here are links to some articles.

Turning 'em loose, an article that appeared in the Las Vegas Review Journal on May 19, 2002, about the possible effects of this study.
Specifications, computing help crack payoff code, an article that appeared in the Las Vegas Review Journal on May 19, 2002, about how I did this study.
One-Armed Bandit or Robin Hood? , an article by myself for Contingencies Magazine explaining the methodology, results, and weaknesses of the study.
Sheraton slots atop list of nickel video payouts, an article that appeared in Memphis' The Commercial Appeal on September 15, 2002 about how this study was used to rank the Tunica casinos.
Play by the rules and the one-armed bandits will still win. Boston Globe article about slot machines, in which my Las Vegas survey is mentioned and my advice quoted. (cache)

My Slot Machine resources

Go to slot machine appendix 3B (Jean/Primm slot returns).
Go to slot machine appendix 3D (Henderson slot returns).
Go to slot machine appendix 3E (Las Vegas quarter and dollar slot returns).
Go to slot machine appendix 3F (Montreal slot return).
Go back to slot machines.