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A Comprehensive Guide to Slot Machine Classification

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Different types of slot machines, derived from its classification.

Types of Slot Machines

There are many types of slot machines available to play and, if you are new to the world of slots, the terminology might leave you confused. We will walk you through the most common type of slot machines and give you useful information about each kind.

Slot machines can be grouped in the following ways: 

  • Types of gameplay: These kinds of slots include progressive, video, and classic slots.
  • Location: This refers to whether the slot game is land-based or available online.
  • Denomination Accepted: Slot games can be divided by the type of coin or bill that can be placed for a single bet. 
  • Number of Paylines and Reels: Some slot games have only three reels and a limited number of paylines. Other games could have way more paylines and 10+ reels.
  • Class: This refers to the legal classification of slot games for regulatory purposes. 
  • Payback Percentage: Slot machines can be sorted by their Return to Player (RTP).
  • Interaction Level: Players can have high or low interaction with the slot machine. 

Types of Gameplay

Classic Slot Machines

Classic slot machines pay homage to the old-school slot machines. Most classic-style slot machines feature 3 reels and 1 payline and have limited betting options. This type of game is ideal for gambling newbies who want to get the feel for how to play a slot machine. You won’t be distracted by graphics or complicated bonus games. Experienced gamblers also enjoy playing classic slot machines because the simplicity creates feelings of nostalgia.

Classic slot machine drums.

Video Slot Machines

Land-based video slot machines have a display screen with graphical reels. Because these games aren’t constrained by physical reels, they can feature more reels than a classic slot game and potentially thousands of paylines. In addition to providing extra chances to win, video slot machines also feature fun graphics and bonus rounds. The innovation of such machines make them a favorite in the gambling community. 

People playing video slot machines in a casino

3D Slot Machines

3D slot machines are a rather new addition to the gambling world. These machines use gorgeous three-dimensional graphics to make players feel truly immersed in the experience. When you play a 3D slot machine, it isn’t just a game anymore. It feels like a cinematic experience.

Multiplier Slot Machines

A multiplier slot machine has a payout ratio that is directly tied to the number of coins that you wager. For instance, betting one coin and landing three symbols on a reel could net you $5. But, if you had bet two coins, you could have gotten $10 instead. Usually, multipliers will payout proportionally in relation to the number of coins that you bet, with the exception of the biggest payouts. In those cases, the payout is much larger when you place the maximum bet. 

Most modern slot machines are multiplier machines. You can still play them with single coins, but many gamblers prefer to place the maximum bet in order to increase their win potential. 

Progressive Slot Machines

Progressive slot machines take a small percentage of each bet and add it to the jackpot prize pool. This number grows higher and higher, until a lucky player eventually hits the winning combo. When this happens, the jackpot is reset to the original amount and the process begins anew. 

Some progressive slot machines are standalone, which means that they are not connected to any other slot games. Local progressive slot machines, on the other hand, are connected to other machines in the same casino. This could range from just a handful of machines to over a hundred. The larger the network is, the higher the potential jackpot becomes. For the largest potential jackpot, you will need to play on a wide-area progressive slot machine. This connects slot machines from all across the same state or country, which can lead to the jackpot being over $1 million. These are the machines that are responsible for the insane slot wins you read about online.

When you play a progressive slot game at an online casino, it will be connected to a huge number of other virtual machines. More people play these on a daily basis than what a physical casino could facilitate. This allows the jackpots to rise to astronomic proportions. Take, for instance, Mega Moolah, which has made multi-millionaires out of several people. 

Huge win in one of the best progressive jackpot slots - Mega Moolah.

Flat Top Slot Machines

Flat top slot machines have a fixed jackpot that players cannot exceed. Such machines likely won’t have a huge jackpot, but your odds are hitting one are better. 


Land-Based Slot Machines

Land-based slot machines can be played physically and are mostly found in real casinos. However, you can also find land-based slot machines in airports, hotel lobbies, and other places. 

Online Slot Machines

Online slots are found in online casinos and you can enjoy playing them from your own home or anywhere else you desire. You can play any time of day or night, and they offer a level of convenience that land-based machines just can’t beat. Want to find out if it matters at what time you decide to gamble? Check out our article on the best time of day to play slots.

Denomination Accepted

Slot machines vary in the denomination that they accept. Some common denominations per spin include $0.01, $0.25, $0.50, $1, $5, and $10. This number can climb even higher, such as the Bellagio’s $1,000-per-payline slot machine. You could even end up spending $5,000 per spin if you activate all five of its paylines. 

Remember, always place the maximum bet in order to fully optimize your chances of winning. If you can’t afford to place the maximum bet on a machine, it may be worth your time to move to a lower-denomination slot machine. 

Number of Paylines and Reels

Classic slot machine may only have five reels and one payline, whereas more advanced slot machines could feature 5+ machines and hundreds of paylines. When you play a slot game online, you will commonly find that it has 243 ways to win. Some games even offer thousands of paylines! 

The orientation of paylines can also vary from game to game. Traditional slot machines pay out from left to right, but online slot games can have many different kinds of alignment: right to left, both ways, all ways, clusters, and more. 


Many countries separate slot machines into classes for regulatory purposes. Such classifications often depend on the games’ maximum bet limit and maximum prize. For instance, in the UK, a class B1 machine offers a maximum stake of £5 and a maximum prize of £10,000. 

In the US, classifications work a little differently. US slot machines are sorted into two types, Class II and Class III. Class II machines are found in small casinos and players aren’t competing against the house. Rather, because Class II games work like lottery games, players are racing against each other to reach the jackpot. On the other hand, with Class III machines, each spin is independent, and gamblers are playing against the house. 

Payback Percentage

Payback percentage refers to the amount of each bet that a gambler will get back while playing on a slot machine. For example, if a game has a 96% payback percentage, this means that, over time, the player could get 96% of their bet back. The house edge, which is what the casino gets to keep, would be 4%. Slot machines have varying payback percentages, typically ranging from 82% — 98%. 

Interaction Level

Amusement with Prize (AWP) Slot Machine

An AWP game provides a small amount of player interaction, but the game does not depend on the player’s skill. This term is most commonly used in the UK and are also referred to as fruit machines.

Skill with Prize (SWP) Slot Machine

A SWP game is very interactive, and its outcome depends partly on the player’s skill. Such games feature a mix of skill and chance, and the exact ratio depends on the machine. 

Where Can I Play Slot Games?

If some of these types of slot games sound appealing to you, come check out our huge library of games at Bob Casino. You will surely be able to find a game that appeals to you. If you want to try your hand at winning a huge jackpot, try one of our progressive slot games. Give the reels a spin and see if you’ll land a winning combo today!

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