Slot machines are the most popular games in online casinos. BetandSlots presents a closer look at how slots are programmed.

Slot machines are the most popular games in online casinos. And in Las Vegas of course! Here we want to take a closer look at how slots are programmed. If you look at the range of casino games, you will find out that the slots area always offers the largest selection of games to play online.

We hope that in this BetandSlots article we can show you how an online slot works technically.

4.8 rating
Welcome Package - Get Up To €1500 & 150FS
18+ Gamble Responsibly.
T&Cs Apply
Minimum Deposit Is €10, Wager X35 Within 7 Days. The bonus is only credited to accounts with fully completed profiles. General Terms & Conditions Apply. Please Read Bonus Terms At Casino's Promo Page. 18+ Gamble Responsibly. T&Cs Apply.
4.8 rating
HighRoller Package - Get Up To €3000 Welcome Bonus
On Your First 3 Deposits
T&Cs Apply
Bonus Available On Your First 3 Deposits. 1st, 2st, 3th As Shown 100%, 70%, 110% Bonus. Min. Deposit Is €300. Please Read The General Bonus Terms. 18+ Gamble ResponsiblyT&C Apply
4.8 rating
Welcome Offer 100% Up To 1BTC or €100
Only For New Players
T&Cs Apply
Only For New Players, Min. Deposit €20 or 0.006 BTC, Wagering Requirments X30, Max Wager Is €5 or 0.001 BTC. Please Read Bonus Terms. 18+ Gamble Responsibly. T&C Apply
4.8 rating
Welcome Bonus Up To $/€100
+ 100 Free Spins

T&C Apply
T&Cs Apply
T&C Apply Visit Casino For Full Terms & Conditions. 18+ Gamble Responsibly.

How slots are programmed – The random number generator

The heart of every slot machine is the so-called random number generator. These number generators are part of every machine and are activated any time you click the spin button hoping to win some real money.

Welcome Package
Get Up To €1500
+150 Bonus Spins
18+ Gamble responsibly
4.8 rating
9.63
T&Cs Apply
Minimum Deposit Is €10, Wager X35 Within 7 Days. The bonus is only credited to accounts with fully completed profiles. General Terms & Conditions Apply. Please Read Bonus Terms At Casino's Promo Page. 18+ Gamble Responsibly. T&Cs Apply.
Welcome Bonus
Get Up To €3000
HighRoller Package
On Your First 3 Deposits. 18+ Gamble Responsibly
4.8 rating
9.63
T&Cs Apply
Bonus Available On Your First 3 Deposits. 1st, 2st, 3th As Shown 100%, 70%, 110% Bonus. Min. Deposit Is €300. Please Read The General Bonus Terms. 18+ Gamble ResponsiblyT&C Apply
Bitcoin Bonus
Get 100% Bonus
Up To €100/Btc
18+ Gamble Responsibly. T&C Apply
4.8 rating
9.55
T&Cs Apply
Only For New Players, Min. Deposit €20 or 0.006 BTC, Wagering Requirments X30, Max Wager Is €5 or 0.001 BTC. Please Read Bonus Terms. 18+ Gamble Responsibly. T&C Apply
1st Deposit Bonus
Up To $/€1500
For High Rollers
T&C Apply
4.8 rating
9.55
T&Cs Apply
T&C Apply Visit Casino For Full Terms & Conditions. 18+ Gamble Responsibly.
Welcome Bonus
Get Up To €/$ 500
+100 Free Spins
T&Cs Apply.
4.8 rating
9.51
T&Cs Apply
Min. Deposit Is €/$10, Max single bet allowed €/$100. General Terms & Conditions Apply. Please Read Bonus Terms At Casino's Promo Page. 18+ Gamble Responsibly. T&Cs Apply.
Welcome Offer
25 Bonus Spins
New UK Players
18+ Gamble Responsibly.
4.8 rating
9.50
T&Cs Apply
Min. Deposit £15, New Players Only, Wagering X35 Within 21 Days. Full Terms Apply. 18+ Gamble Responsibly. Please Read The Bonus Policy. T&C Apply
Welcome Bonus
Up To €260 Total
75 Free Spins
18+ Gamble Responsibly. T&C Apply
4.7 rating
9.40
T&Cs Apply
Bonus wager X40, Max. bonus amount €60, Max. win with bonus €400, Min. deposit amount from €20, Free spins 5 times by 15, Activation after playing off the X1 deposit within 23 hours upon receipt, Free spins wager X35, Max. win with free spins €200. General Bonus Terms And Standard Terms & Conditions Apply. Please Read Details At Casino’s Offer Description. 18+ Gamble Responsibly. T&C Apply
Welcome Bonus
Get Up To €700
+150 Bonus Spins
4.7 rating
9.40
T&Cs Apply
Minimal Deposit €/$20 or Equivalent Currency. Wagering Requirments Must Be Met And Used in Any Qualifying Slot Game. Please Read General & Bonus Terms And Conditions At Casino's Offers Page. 18+Gamble Responsibly.
T&C Apply
Welcome Package
€7 Free
No Deposit Bonus
18+ Gamble Responsibly. T&C Apply
4.7 rating
9.38
T&Cs Apply
First Time Players Only, Wager X40, Any Winnings From The Free Bonus or Free Spins Is Limited To €/£/$200, The Players Should Be Withdrawn Only The Maximum of The Winnings. Please Read Full Bonus Terms At Casino's Bonus Terms. 18+ Gamble Responsibly.T&C Apply
Welcome Bonus
3000% Up To $9000
For All Rival Slots
18+Gamble Responsibly. T&C Apply
4.7 rating
9.35
T&Cs Apply
Minimum Deposit Is $100 And Max. Deposit Is $300. Wager X45, Please Read General & Bonus Terms And Conditions At Casino's Offers Page. 18+Gamble Responsibly.
T&C Apply

Each RNG number represents a symbol on the slot machine. Depending on which combination of numbers the generator spits out when the reel stops, you see a combination of symbols. If these symbols are on the same payline, you win. If this is not the case, it is an unsuccessful spin.

The most important point on the Random Number Generator is the fact that this system has no memory or history. This means that every result of the RNG does not depend on previous results.

Every result of the generator is therefore purely coincidental. You can compare it to the game results in roulette. Again, each game result is completely independent of the result of the previous game round.

Are slots really random ?

Large software manufacturers invest a lot of money to ensure that the RNG is correctly programmed.  These manufacturers and online casinos themselves commission external companies to test the slot machines for correct functionality. Also to check that the payback percentage is according to standards in the long run.

These third-party companies periodically test all slot machines. This ensures that the random number generator works properly and without errors in the respective mobile casino.

Probabilities of winning and RTP

However, there is a probability that a certain symbol will appear at a certain point, which can be calculated. Assuming that a slot has three reels, three rows, and three different symbols, of which only one is a winning symbol and also that there is only one winning line, the number of possible combinations on the monitor would be exactly 3x3x3, 27 in total . 

Since only one combination, namely three winning symbols on a winning line, wins, the probability of winning is 1/27 = 0.037 or 3.37%.

In other words, if the game was long enough, the winning combination would appear on average in every 27th game. If the winnings were exactly 27 coins, this would also correspond to a payout ratio of 100%. 

However, as usual, the payout ratio is reduced by the so-called “House edge”, or the casino advantage. In the example, a payout of 26 euros would correspond to a payout ratio of 96.3%. This number is the RTP, meaning Return To Player.

Another option would be to insert zero profit symbols or symbols with a very low value. Most of these are the well-known playing card symbols or the lemons in the “fruit” machines.

What should I do if I think a slot machine is rigged?

While it is unlikely, a slot machine may malfunction. If people are affected by such a malfunction, it is important that slots players act correctly.

First of all, while playing slot you should take a screenshot of the game the moment the malfunction occurred. With this screenshot, you should then contact the customer service of the online casino operator immediately. 

Here you have the so-called log files of each spin available and the casino can understand whether it is actually a bug in the game.

Such a scenario is rather unlikely, but if it does occur, the most important thing is that you have a screenshot of the malfunction, otherwise it can be difficult to prove this malfunction.

How do slots work – Slot variants

The slot machines have the modern 3D video slots with some very many paylines, classic slots such as the “fruit” and “diamond” slots and the so-called jackpots. 

But video poker, as well as table and card gaming, are fundamentally not designed differently, only that additional rules of the game sometimes apply. In video poker, if the game is skillful and there is a paytable that fits the perfect game, payout ratios of over 100% are possible.

Many slots also have so-called gamble features. There is a chance to double, triple or even quintuple a win by playing another 50:50 game with guessing cards or colors. So-called multipliers, multiply your winnings, are also in the latest slot machines versions. In addition, many slots have a free spin mode, in which players can make winnings without straining their own bankroll when spinning.

Other games, including progressive jackpots, where the amount of the jackpot increases, the more players play the game also have bonus rounds. If several bonus symbols appear, there is a chance within the bonus rounds to achieve high winnings or even hit the jackpot.

The best-known game programmers include NetEnt, Novomatic, Merkur, Microgaming, Evolution, Yggdrasil, Bally or PLAY’n GO, etc.

Conclusion

Of course, there are many different types of slot machines. Some have five reels and 100 paylines and some have only three reels and five paylines. In principle, however, all slot machines work the same.

In the center of every slot machine are the so-called Random Number Generators. Those always determine the outcome of your spin. It is also important to be aware that a previous game round cannot influence the outcome of the next shoot. It is therefore completely irrelevant whether you won or lost in the previous shoots. Your chances of winning are always the same.

We hope that this article has given you an understanding of how slot machines are programmed. Now it is up to you whether you are lucky and become a slot winner at the numerous slot machines in the various online casinos.

Slots Frequently Asked Questions

What is a slot machine?

The slot machine, known variously as a fruit machine, puggy, poker machine/pokies, or simply slot, is a casino gambling machine that creates a game of chance for its customers.

When were slots invented?

In 1887 the first poker gambling machine was invented. It had 5 reels with a total of 50 cards on each. In order to increase the house edge the ten of spades and the jack of hearts were left out, which reduced the odds for a royal flush by half. This machine was placed in bars and it costed a nickel (5 cents) to play. It didn’t have a direct payout mechanism, so wins were paid at the bar.

When do slots payout?

Charles Augustus Fey invented the first slot machine which allowed automatic payouts in 1891. He reduced the complexity of reading a win, by replacing the 5 reels with just 3 and the 50 different playing cards with just 5 symbols – hearts, diamonds, spades, horseshoes, and a liberty bell. The highest payout was awarded for 3 bell symbols since the machine was named Liberty Bell. Since then, slot machines pay customers on the original logic, no matter how complex they have been evolved since!

Are slots rigged?

No one can be 100% certain. But best online casinos and operators with a valid license have all their online games periodically tested by third-party companies. This ensures that the random number generator works properly and without errors in the respective mobile casino. So, serious and trustworthy casinos have really random and honest slots.

Top Casino Reviews
iLucki Casino
iLucki Casino

Welcome Offer - Up To €/$ 500 & 100 Free Spins
18+ Gamble Responsibly

New Vegas Casino
New Vegas Casino

Insane Welcome Bonus - 3000% Bonus Up To $9000 On All Rival Slots
18+Gamble Responsibly.

Casino 1xSlots
Casino 1xSlots

Welcome Package - Get Up To €1500 & 150FS
18+ Gamble Responsibly.

Slotman Casino
Slotman Casino

Welcome Bonus - Get Up To €700 & 150FS
18+ Gamble Responsibly.

Grand Eagle casino
Grand Eagle casino

Grand Eagle Casino - Welcome 100% Match Bonus Up To $300
21+ Gamble responsibly

SOL Casino
SOL Casino

Welcome Bonus - 200% & 75 Free Spins On First Deposit
18+ Gamble Responsibly.

Fortune Clock
Fortune Clock

Welcome Package - A Total of 225% And 225 Free Spins
18+ Gamble Responsibly.

Gratorama
Gratorama

Welcome Package - €7 No Deposit Bonus
18+ Gamble Responsibly

Vstar Bet Casino
Vstar Bet Casino

Welcome Casino Bonus - 100% Up To £200 On First Deposit
18+ Gamble Responsibly
T&C Apply.

Sons of Slots Casino
Sons of Slots Casino

Welcome Bonus - 50% Up To €400 & 50 Free Spins
18+ Gamble Responsibly

SlotWolf Casino
SlotWolf Casino

HighRoller Package - Get Up To €3000 Welcome Bonus
On Your First 3 Deposits

Greenspin casino
Greenspin casino

First Deposit Bonus - Get Up to $1000 & 300 Free Spins
3 Bonus Codes Available
18+ Gamble Responsibly

Volt casino
Volt casino

Welcome Offer - Get Up To 300 Wager Free Cash Spins
First Deposit Bonus

GoPro Casino
GoPro Casino

25 Bonus Spins For UK New Players.
18+ Gamble Responsibly

Slotum casino
Slotum casino

Welcome Bonus Up To $/€100
+ 100 Free Spins

T&C Apply

Betfinal
Betfinal

Casino Welcome Package Up To $1350
Register Now

SlotV casino
SlotV casino

Get Up To €600 And 175 Free Spins
On Your First 3 Deposits.

Vegas Crest Casino
Vegas Crest Casino

Welcome Bonus Get Up To $2500 And 100 Free Spins
Only For New Players.

Wildblaster Casino
Wildblaster Casino

Welcome Offer 20 Free Spins No Deposit Bonus
Claim It Before Deposit!

London Betting Shop
London Betting Shop

Bookmaker Bonus $30 Free For Account Verification
Use Coupon Code Provided

Jonathan Stefanou

Author: Jonathan Stefanou

Friends call me Jo and I am a professional writer contributing at Betandslots from the first day! Through the past two decades and right after my graduation as a journalist, I’ve been covering international sports for various newspapers and magazines.


Read more