Understanding Slot Machines

If you haven’t played a slot machine in a few years, be prepared for a surprise. They are not the one-armed bandit of even ten years ago. Many modern day slot machines don’t have a handle, nor do they take coins. Instead, you insert a bill or a voucher, pick the number of lines, the number of credits and push a button. Slot machines can no longer be described as “one size fits all.” They are fun, but sophisticated machines, and are available in several combinations of components. To play slot machines today, it is helpful to understand them.

Types of slot machine reels

Generally, slot machines have one of two types of reels: Mechanical-reel slots and video slots, which display virtual reels. The traditional slot machine had three mechanical reels. Three reels is still the standard for a mechanical-reel machine, but there can be up to five reels. Video slots typically display five virtual reels.


Slot machine plays come in all denominations, from ½ cent per line (you get to play two lines per penny) to $25 or more per line. Typically, the denominations will be between 1 cent and $5 dollars. Some of the newer machines allow you to choose the denomination you wish to play. These are called multi-denomination machines.


The old fashioned slot machine had one payline, that of the middle display. Current machines can have 50 lines, and some machines determine winners if winning symbols match on the first three reels. And some five-reel machines enable you to win if winning symbols “wrap-around, ” i.e., a winning combo on reels 5,1 and 2. A three-reel mechanical machine will typically have between one and five paylines. Video slots, however, will typically have between nine and thirty paylines.

Cost of a spin

Denominations and paylines determine how much money you will pay for a spin. This is why some players will state that a penny machine costs as much as a dollar machine. Generally, dollar machines come in the traditional, three-reel, one payline machine, which you can play up to two or three credits for that line. Penny machines, however, contain twenty or thirty lines and many allow you to play ten-cents per line. If you put in the maximum amount of money allowed, both denominations will cost you $2 – $3.

You do not have to play max credits on a penny machine. If you play one credit per line, and play all lines, you could spin the reels for twenty-cents. Or, you could play ten credits on just the first line and spend ten-cents. The lower denomination machine does give you more flexibility on how much money to spend.

The amount of money you spend, however, affects the amount of money you win should you spin a winning combination. If you don’t play all lines, and a winning combination appears on a line you did not play, you will not win anything on that spin. If you win on a line on a penny machine, the winning is based on that line only, so it is still possible to lose money on the spin (you just don’t lose all your money). You can win something on twenty paylines, and come out barely ahead, or win one one payline and enjoy a significant win. The possibilities are numerous. When thinking about money management, consider how much a spin will cost, and how much you can potentially win on a spin. Even at twenty-cents at a time, a hundred dollars can go by within minutes.

Bonus plays

Many slot machines incorporate bonus games. These are wins outside of lining up winning combinations. Sometimes the wins are exciting, sometimes you will only get your money back. However, for many people, triggering a bonus creates joy. There are three types of bonus games: The top box bonus game, the pick-em bonus, and the free spin bonus.

The top box bonus is generally a free spin on a wheel located on top of the slot machine. The player wins the amount of money the pointer lands on. Another variation is on machines which a winning number of credits lights up on the top display of the machine, which the player is awarded. Pick-em bonus games present the player a number of symbols to choose from. When the player picks a symbol, the winning credit displayed behind the symbol is awarded to the player. Free spin bonuses are just that, a selected number of free spins is awarded to the player. Sometimes wins during the free spin plays are multiplied.

Different machines employ different ways of triggering the bonus. On three-reel machines, it is usually triggered by either three bonus symbols on a payline, or a bonus symbol on the last wheel. Video slots usually trigger a bonus game when three bonus symbols appear on the screen. Depending on the game, these symbols can appear anywhere on the screen, on any three consecutive reels, anywhere on the first three reels, or as a winning combination on the first three reels. If you are not sure, read the instructions on the slot machine.

The progressive

Many slot machines also employ progressive jackpots. The word, “progressive” excites many players. However, there are many types of progressive jackpots, some of which are modest amounts. Simply, a progressive jackpot is a jackpot that grows over time until someone hits it. They can range to less than $100 on some penny machines, to over a million dollars.

Progressives also come in many varieties. Progressive jackpots can be for a single machine, a bank (i.e., row) of machines, casino-wide, or jurisdiction-wide (i.e., all of the state of Nevada, or all Native American casinos across the country). There can be one huge jackpot, or different levels of progressive jackpots. Progressives can be won with a winning combination, or they can be “mystery” progressives.

The progressive jackpot amount on single-machine progressives apply to that particular machine only. These are usually the slowest growing progressives and also the smallest amount. Sometimes, they are less than the amount that can be won on a top spin. Some progressive jackpots apply to a certain bank of machines, or to certain types of machines throughout the casino. The most anticipated progressive jackpots by players are the ones that grow to hundreds of thousands of dollars and into the millions. These machines are linked to machines across the state or even the country. Sometimes there are levels of progressives. On these types, the top progressive may reach an impressive, but not mind-boggling, and the smaller progressives may be less than what you would win on a regular spin.

Winning a progressive jackpot is just as varied as there are variations of progressives. Progressives can be won by lining up progressive symbols on a payline, through a bonus game, or be random. The life-changing progressives are usually won when the progressive symbol lines up in a winning combination on a payline. Multi-line slot machines do not provide an advantage here, as usually only one line is usually designated as eligible for the progressive jackpot. Multi-level progressives usually employ either a bonus game strategy or are mysteries. When winning is through bonus games, you accumulate bonus points and your “score” will determine the jackpot level. On mystery progressives, the machine will lock up without warning and display a message which level of progressive you have won. You do not have to have a winning spin to be awarded a mystery progressive.

In addition to the way to win a progressive, most progressive jackpots contain monetary conditions. Some progressives can only be won when the player plays max credits. On a dollar machine, this usually means $3.00, and on a penny machine, this usually means between $1.50 – $3.00. Some progressives, however, have a separate “ante,” if played, qualifies the player for the progressive jackpot(s).

The symbols

Symbols on a slot machine can fit into four categories: straight symbols, multipliers, wild symbols, and scatter symbols. Multipliers are symbols that multiply a winning combination. They can double, triple or even pay ten times a normal amount. They are also wild, substituting for other symbols. Scatter symbols are symbols that do not need to appear on a winning payline to trigger a win.


RNG stands for Random Number Generator. All slot machines contain this. It is the program which determines if the spin will win, and how much. It is constantly running, even when the slot machine is not being played. The spin result is determined by the combination it generated when the spin button was pressed. Therefore, a difference of a second will determine a different outcome. Note that there are significantly more losing combinations programmed into the RNG, so it’s likely that you will lose on any given line on any given spin.

The Help button

The modern slot machine can be complicated to understand. Several of the video slot machines may look alike, but the way to play them can be significantly different. Most slot machines, especially the video slots, contain a “Help” button, which explains the symbols, the pays, the paylines, the bonus games, and the requirements to trigger bonus games, instructions to play the bonus games, and the requirements to win the progressive jackpot(s). Before playing any game you’ve never played before, press the “Help” button and read the instructions.

Slot machines are a form of entertainment, and playing slot machines can be a very expensive hobby. Control your play, don’t let the play control you. Knowing how the games work help make playing slot machines more enjoyable. Knowing how much each game costs and the rewards each game offers help you manage your money.