• Appendices
• Slots Analysis
• Miscellaneous

Introduction

When it comes to gambling, the easier a game is to understand the worse the odds usually are. This is certainly the case with slot machines. Playing them is as easy as pressing a button. However, between the high house edge and fast rate of play, there is no quicker way to lose your money in a casino.

To see how slots pay less than true odds to give the house an edge, let’s set up an example that’s as streamlined as slot odds can get, a game of the type used in the early decades after Charles Fey invented the three-reel slot machine in 1895. A hypothetical three-reel slot game with one 7, two bars, three cherries and four watermelons per. Understand this one point clearly from the beginning, and you’ll be way ahead of most of the so-called slots experts on the Internet: slot machine results are random. Your chances of winning at a slot machine game are random, and there’s nothing you can do to affect the outcome on any specific game. Slot machines offer players a fantastic opportunity to win with each spin of the reels, through bonus offerings, incredible in-game features and line and bet multipliers, or simply winning by getting lucky the old-fashioned way. Slot machines are a phenomenal way to spend your time, offering hours of entertainment and chances to win big.

Before going further, let me make clear that this page addresses the way slot machines work in most parts of the United States and the world. However, some parts of this page do not apply everywhere. For example, I state that slot machines have a memory-less property, where the odds of every spin are the same. In some places, like the UK, some machines in bars, called 'fruit machines,' have a mechanism that guarantees a certain profit over the short run, which causes the game to go through loose and tight cycles. These games do not have the usual independence property of the major slot makers.

How They Work

Whether you're playing a 3-reel single-line game or a 5-reel 25-line game, the outcome of every bet is ultimately determined by random numbers. The game will choose one random number for each reel, map that number onto a position on the reel, stop the reel in the appointed place, and score whatever the outcome is. In other words, the outcome is predestined the moment you press the button; the rest is just for show. There are no hot and cold cycles; your odds are the same for every spin on a given machine.

Slot machines are just about the only game in the casino where the odds are not quantifiable. In other words, the player doesn't know how the game was designed, so it is difficult to look at an actual game to use as an example. So, to help explain how they work, I created the Atkins Diet slot machine (link). It is a simple, five-reel game with a free spin bonus round, much like IGT's Cleopatra game.

For information on how it works and all the odds, please visit my Atkins Diet par sheet.

For a more complicated example, featuring sticky wilds in the bonus, please try my Vamos a Las Vegas slot machine.

For information on how it works and all the odds, please visit my Vamos a Las Vegas par sheet (PDF).

Odds

The following table shows the casino win for Clark County Nevada (where Las Vegas is) for all slots for calendar year 2012. They define 'slot' as any electronic game, including video poker and video keno. I've found video keno to be about equally as tight as reeled slots, but video poker has a much higher return. So, the return for reeled slots should be higher than these figures.

Clark County Slot Win 2012

Source: Nevada Gaming Control Board, Gaming Revenue Report for December 2012 (PDF, see page 6).

Most players play penny video slots. Based on past research, I find the house edge on those to usually be set from 6% to 15%. In general, the nicer the casino, the tighter the slots.

Advice

While there is no skill to playing slots, there is some skill in selecting which machine to play and ways you can maximize your return. What follows is my advice, if you must play slots at all.

• Always use a player card. Slots may be a lousy bet, but the casinos treat slot players very well. A $1 slot player will probably get comped better than a $100 blackjack player. Of course, don't play for the reason of getting comps. You'll give them a lot more than they'll give you.
• The simpler the game, the better the odds. The fancy games with big signs and video screens tend to not pay as well as the simple games. However, slot players always tell me the fancy games are more fun.
• The higher the denomination, the better the odds. For that reason, it is better to play one coin per line on a 5-cent game than five coins per line on a 1-cent game.
• Don't forget to cash out and take your ticket when you leave. It is easy to forget after hitting a jackpot.
• Try to play slowly and as little as possible to get your fix.
• In some games there is a skill feature, like Top Dollar. In such games, advice is usually offered, which you should take.

Myths and Facts

Just about everything that players believe about slots is untrue. Here are the most common myths and facts. As a reminder, this page is based on slot machines commonly found in the United States. Some machines, like 'fruit machines' found in the United Kingdom work differently.

• Myth: Slot machines are programmed to go through a cycle of payoffs. Although the cycle can span thousands of spins, once it reaches the end the outcomes will repeat themselves in exactly the same order as the last cycle.

  Fact: This is not true at all. Every spin is random and independent of all past spins.

• Myth: Slot machines are programmed to pay off a particular percentage of money bet. Thus, after a jackpot is hit the machine will tighten up to get back in balance. On the other hand, when a jackpot has not been hit for a long time it is overdue and more likely to hit.

  Fact: As just mentioned, each spin is independent of all past spins. That means that for a given machine game, the odds are always the same. It makes no difference when the last jackpot was hit or how much the game paid out in the last hour, day, week, or any period of time.

• Myth: Machines pay more if a player card is not used.

  Fact: The mechanism that determines the outcome of each play does not consider whether a card is used or not. The odds are the same with or without one.

• Myth: Using a player card enables the casino to report my winnings to the IRS.

  Fact: That makes no difference. If you win $1,200 or more they will report it either way. If you have a net losing year, which you probably will, at least the casino will have evidence of it. Such annual win/loss statements may be used as evidence to declare offsetting loses to jackpot wins.

• Myth: The slot department can tighten my game with the press of a button remotely. Thus, you better be nice to the staff and tip them well, or they will use a remote control to have the machine take you down in a hurry.

  Fact: There is now some truth to the myth that the odds of a machine can be changed remotely. Such 'server-based slots' are still experimental and in a minority. Even with server-based slots, there are regulations in place to protect the player from the perceived abuses that could accompany them. For example, in Nevada a machine can not be altered remotely unless it has been idle for at least four minutes. Even then, the game will display a notice that it is being serviced during such changes. (source) Meanwhile, for the vast majority of slots, somebody would physically need to open the machine and change a computer chip, known as an EPROM chip, to make any changes.

• Myth: The machines by the doors and heavy traffic flow areas tend to be loose while those hidden in quiet corners tend to be tight.

  Fact: I've studied the relationship between slot placement and return and found no correlation. Every slot director I've asked about this laughs it off as just another player myth.

• Myth: Slots tend to be looser during slow hours on slow days of the week. However, when the casino is busy they tighten them up.

  Fact: Nobody would take the trouble to do this, even if he could. The fact of the matter is the casinos are trying to find a good balance between winning some money while letting the player leave happy. That is best achieved by slots loose enough to give the player a sufficiently long 'time on device,' as they call it in the industry, with a reasonable chance of winning so he will return to the same casino next time. If the slots are too tight, the players will sense it and be unlikely to return.

  The kind of place you're likely to find tight slots are those with a captive audience, like the Las Vegas airport. So, if the slot manager feels that 92% is the right return for a penny game, for example, he is likely to set every penny game all that way, and keep them that way for years.

Play

Reviews

• Dazzle Me (NetEnt)
• Mr. Vegas (Betsoft)
• Sparks (NetEnt)

Internal Links

• Appendix 1 shows the details and analysis of almost 4000 actual spins on a Reno slot machine.
• Appendix 2 shows an example of the virtual reels behind a hypothetical slot machine and how the average return is calculated.
• Appendix 3A: 2003 Las Vegas slot machine rankings.
• Appendix 3B: 2002 Jean/Primm slot machine rankings.
• Appendix 3C: 2002 Tunica slot machine rankings.
• Appendix 3D: 2002 Henderson/Lake Mead slot machine rankings.
• Appendix 3E: 2002 Quarter and dollar returns for Las Vegas slots
• Appendix 4 shows how the return is calculated for my Wizard's Fruit Slot Machine.
• Appendix 5 analysis of the 21 Bell Slot Machine.
• Appendix 6 Analysis of Red, White, & Blue Slot Machine.
• Lock and Roll analysis of the skill-based slot machine found in North Carolina.
• Deconstructing Jackpot Party analysis of the video slot machine.
• Deconstructing Lion's Share analysis of the classic MGM progressive game.
• Deconstructing Cleopatra analysis of the popular IGT game.
• Deconstructing Lionfish analysis of the slot game found on many Game Maker machines.
• Deconstructing Megabucks.
• Deconstructing the Atkins Diet slot machine.
• Deconstructing Lucky Larry's Lobstermania.
• Deconstructing Hexbreaker.
• Deconstructing Blazing Sevens.
• Deconstructing Hot Roll.
• Mystery progressives on Ainsworth slots.
• Mystery progressives on WMS slots.
• Baltimore Sun article, in which I am quoted.
• 100% Rebate on Slot Losses Promotions: When to quit playing when all losses are refunded.

External Links

What Are Your Odds On Slot Machines Win

• For a simplified explanation of slots, please see my companion site Wizard of Vegas
• German translation of this page is available at richtigspielen.com
• Another decent overview of how slots work and some practical advice for playing them is How Slot Machines Work at VegasClick.com.
• PAR Sheets, probabilities, and slot machine play: Implications for problem and non-problem gambling by Kevin A. Harrigan and Mike Dixon, University of Waterloo, Waterloo, Ontario, Canada. This is an outstanding academic paper that details how some popular slot machines were designed.
• PAR Sheets, probabilities, and slot machine play: Implications for problem and non-problem gambling - Academic paper based on the par sheets for some modern slot machines

So who pays for those Volcanic eruptions? Pirate Battles? Carnival Parades? and Glittering Showrooms? Slot Machines. 60-65% of casino revenue is generated by those bell-ringing one armed bandits that seem to multiply on casino floors like rabbits. So how does the average player gain an advantage and possibly win? Well... aside from cheating (which we really don't suggest you get involved in) the only way to gain some sort of advantage is to choose your slots with utmost care and discrimination.

Slot machines in Las Vegas are required by law to payout 75% of the money that goes into them, actual payout in Las Vegas is approximately 95%. Will you be the one that takes the money instead of gives it? That is up to luck, but with a little investigation one can easily learn to identify which machines are more favorable to the player than others. Slot machines are all about the payout... Red White and Blue, Double Diamond, Dick Fucking Clark, Cherry whatever. At the end of the day what every slot player needs to do is look at the pay schedule on the machine they want to play. Very often the same machine one row over will pay 5,000 credits on 3rd credit jackpot while you're playing on a 2,000 3rd credit machine. Plain and simple you're cheating yourself.

Slot Spotlights

A few notable slot machines we here at VT have found more playable, or more interesting, than the other nonsense out there like Leprachaun's Gold or Tabasco Slots or whatever.

We like machines that have the best payouts on the lowest winning spins. These will keep you going longer between larger wins and not enact the ATM-In-Reverse principle seen at many of the larger joints (Venetian being the worst we've experienced).

100 or Nothing
Red, White and Blue
Slot Machine Jackpots Photo Gallery
Wheel of Fortune
Wild Cherry

What Are Your Odds On Slot Machines Wins

Slot Machine Payback Percentages

Below are the slot payback percentages for Nevada's fiscal year beginning July 1, 2002 and ending June 30, 2003:

5¢ Slot Machines
The Strip - 90.32%
Downtown - 91.50%
Boulder Strip - 93.03%
N. Las Vegas - 92.97%
25¢ Slot Machines
The Strip - 92.59%
Downtown - 94.83%
Boulder Strip - 96.47%
N. Las Vegas - 96.63%
$1 Slot Machines
The Strip - 94.67%
Downtown - 95.35%
Boulder Strip - 96.48%
N. Las Vegas - 97.21%

$1 Megabucks Machines
The Strip - 89.12%
Downtown - 88.55%
Boulder Strip - 87.76%
N. Las Vegas - 89.41%
$5 Slot Machines
The Strip - 95.33%
Downtown - 95.61%
Boulder Strip - 96.53%
N. Las Vegas - 96.50%
All Slot Machines
The Strip - 93.85%
Downtown - 94.32%
Boulder Strip - 95.34%
N. Las Vegas - 95.32%

What Are Your Odds On Slot Machines Jackpots

The Math of Casino Slot Machines

For every dollar you wager in a slot machine, you will lose 100% - Payback% of that dollar. For example, you're at Bellagio playing the $1 Double Diamond slot, wagering Two Credits ($2) per spin. According to the table, for every $2 spin you will lose 5.33% of that bet... just shy of 11¢. Granted these 11 cents don't get extracted instantly... this is computed over time. So if your bank roll limit is $10 it will take you, on average 52 spins before your bankroll is toast (under $1) and you are out of credits.

How was this number derived:

STAKE x (Payback Percentages) = STAKE x (Payback Percentages) = STAKE x (Payback Percentages) = ...
Repeat calculation until the number gets below the minimum bet - if you play long enough, you're gonna go broke. THAT is a FACT. Slot machines are entertaining, relaxing, require little thought beyond pressing a button. IF you want to truly GAMBLE, you might want to look into Video Poker, and eventually Blackjack as other options.

Granted, sometime in there you just might hit that $500 win on the Wheel of Fortune, or The Elvis progressive might shake rattle and roll $1000 your way... but the math inside the machine determines that you will in fact lose a certain percentage of your wager on each spin, and the more you spin... the more you will lose despite short runs of successful jackpots. If you find you are UP... leave. Every spin of a slot machine generates a random number that has NOTHING to do with previous numbers. SLOT MACHINES do NOT run in streaks (even if you might wish to think they do). Don't expect to get any of the money you put into a machine out of it unless you learn to press the CASH OUT button.

Gamblers Library

VT fully recommends the following books to help you decrease the house advantage on casino card games.

What Are Your Odds On Slot Machines Without

What Are Your Odds Of Winning On A Slot Machine

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