How Slots Are Programmed

How Slots Are Programmed

Many decades have passed since the first slot machine was created, but this type of gambling is still one of the most popular in the world. Although these games have undergone many changes, their basic work principles have remained unchanged — you make a bet, start the rotation of the reels, and wait for the results. Previously, you had to use a lever that activated the mechanical device which determined the results of each round; today, a random number generator is responsible for this, it works in accordance with the criteria that the provider set in the game. We will talk more about how slots are programmed in the USA in this article.

Slot Machine Principles of Work & Mathematics

The simple operation principle – this is what attracts millions of customers to slot machines; to start betting, you do not need any special knowledge and skills. Even if you are an absolute newbie who has never played in a casino, you will cope with this task. You only need to complete a few steps:

  • Select a game in the title catalog and launch it.
  • Decide on the bet size.
  • Press the button to start spinning the reels.

If a sequence of identical symbols that corresponds to the payline appears on the reels as a result or you meet another condition, you receive prize money; if none of this happens, you lose.

How Random Number Generator Is Programmed for Slots

Each software provider has a random number generator at its disposal; it lies in the basis of any created game and is used to determine the results of the reel spins. It is programmed so that it is impossible to influence its work or predict the results. The outcome of each individual spin, as well as bonus features, is determined in a split second after the start of the spin.


Casino random number generator
The random number generator is checked by independent audit companies that issue special certificates of conformity

The only regularities that the random number generator observes relate to the observance of the slot operation criteria that the developer has put into it. In the long run, the game should return players the amount of money corresponding to its RTP level.

Are Slots Controlled

The characteristics of the games that the provider creates have to comply with the requirements of the country where the company offers its services to customers. However, the gameplay itself is not controlled by anyone; it remains completely random, regardless of which site you play on and which developers’ slot machines you choose. This creates the sense of excitement for which millions of customers come to the online casinos.

Providers not only create slots and configure them, but also control their performance and conduct maintenance. Due to this, no one except the developer can change their characteristics.

Providers monitor the technical integrity of the created games, their availability online, as well as compliance with the characteristics laid down in them.

Probability & Odds of Winning

The results of previous spins in the slot do not affect future ones in any way; they are not connected. For example, one day you can activate a series of free spins several times in a row, and the next day you can make 200 bets and never see the bonus feature. The initial winning chances in each game are the same.

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Online slots are programmed so that you never know where your next bet will lead.

How Slot Machines Are Programmed: RTP & Volatility

When creating a game, the developer puts dozens of characteristics into it: the number of lines, reels, and rows, payout multipliers, bet limits, maximum prize money, etc. However, these two criteria are the most important ones:

  • RTP. This is the theoretical percentage of return of funds, which shows how much money from the total amount of investments of all players the slot machine will return to them in the form of payments during its working session. The higher this percentage, the more profitable it is to bet in the long run.
  • Volatility. This is a conditional indicator that does not have a numerical expression and affects how strong the spread in the frequency of payments and their sizes will be. As the volatility increases, the series of unsuccessful spins also increase; at the same time, the size of the potential payout increases. Slots with low volatility, on the other hand, pay out prizes consistently often, but their size is usually small.

Try to place bets in games with the highest possible RTP, and choose volatility considering your own interests and the amount on your bankroll. The higher the level of risk, the larger the amount you should have.

House Edge Explained

The RTP ensures the casino advantage in slot machines; in table games, these are special details in the rules that allow the site to receive profit in the long run regardless of the local wins of a few lucky customers.

For example, in roulette one or two zero sectors are available; in baccarat, the payout for the victory of a Banker is lower than 1:1 (the casino charges a 5% commission); in blackjack, there are side bets that give the casino a higher edge.

When Slots Are Ready to Pay

Many gamblers mistakenly believe that slot machines are programmed to pay out at certain times. However, the random number generator calculates the results directly in the process of spinning the reels, so this statement is false.

A slot machine can give you a win at any time, and there is no particular moment when it is better to place bets in it.

You have a chance to receive prize money at any time and as a result of each individual bet.

Tips for Winning Online Casino Slots

Since you cannot influence the RNG and the slots characteristics, you have to use the recommendations for choosing the right games to increase your winning chances. They do not guarantee that you will remain in the black in the end, but slightly increase the likelihood of this outcome.

Play Slots with Fewer Reels & Maximum Paylines

The fewer reels in the slot machine and the more paid lines, the more frequent combinations of identical symbols form on the field. That is, you can increase the frequency of receiving prize money.

Learn Paytables

Before you start betting, take a look at the payout table and make sure that the minimum prize money at least compensates for the initial bet size. In many slots, payouts can be half or even a quarter of the cost of a spin.

Paytable in the slot machine
You can see the paytable and a description of all the mechanics and functions in the Help section of the slot machine

The higher the multipliers, the more profitable your game will be. But do not forget to consider the number of lines in addition to this indicator.

Use Slots with Bonus Rounds

The main way to receive payouts in slot machines is to collect combinations of identical symbols. Besides it, many other features can be implemented, including a series of free spins and bonus rounds.

Free spinsThis is a series of free spins that take place on the same or a slightly modified playing field. Once this feature begins, additional mechanics can be activated to increase the payout potential.
Bonus roundInstead of spinning the reels, you are offered to play a mini game; you may need to choose items, spin the Wheel of Fortune, or open chests.

To switch to these features on the playing field, you need to collect the required number of scatters: 2 or more, depending on the slot machine rules.

Claim All Bonuses & Programs

Due to casino bonuses, you will be able to receive additional benefits at different stages of the game: after registration, for making your first deposit, for making a certain turnover of bets, for progressing through the levels in the loyalty program, or on holidays. These benefits come in the form of cash bonus or free spins.

Before you activate a specific bonus, we strongly recommend that you study its activation and wagering conditions. You will not be allowed to immediately withdraw the received money; first, you will need to fulfill several requirements.

Prefer Smaller Jackpots

A large multi-million dollar jackpot is good, but the chances of winning it are almost non-existent in practice. Therefore, it makes sense to choose a fixed jackpot instead of a progressive one. Although its size is not so large, you will have a real opportunity to receive it. These jackpots are at stake in hundreds of slots, and there may be several separate prize pool levels at once in some gambling games.

Slot Machine History

The author of the first slot machine is Charles Fey. The inventor gave his brainchild the Liberty Bell name and equipped it with 3 reels and 3 rows with 1 payline. To start the game round, it was necessary to place a coin in the slot and pull the lever. If a line of three identical symbols formed on the reels as a result, the player received prize money. The results were determined not by a random number generator, but by a mechanical device that set the reels in motion. At that time, the slot machines operation was still not regulated in any way, so it had a low return rate compared to modern games. Despite this, the novelty was very liked by both ordinary casino customers and owners of gambling venues.

For many years, slot machines were programmed in the USA following the example of Liberty Bell, until the mechanical reel spinner was replaced with a digital block with a random number generator. Despite the fact that the first slot machine had an extremely low RTP and many other shortcomings, it laid the foundation for the development of this gambling category.


No. They are programmed to bring income to the casino and the provider. Due to the fact that RTP applies to the total amount of bets and not to individual users, each player has a chance to stay in the black.

Yes. If the slot machine is licensed, then its operation characteristics are the same regardless of what gambling site it is available on.

No. All slot machines are only available online, and you won't be able to download them to your device. You can play on your smartphone through the website version or the separate mobile app.

Yes. You can bet virtual chips in demo versions, but it is impossible to receive real money payouts in this game mode.

It depends on the maximum payout in a particular slot machine. Some of them allow you to win no more than x1,000 from the bet, while in others the maximum prize is x100,000 or more.

Publication Author
Donald Peterson
Author of articles
Donald Peterson is an avid gambler from Edmonton, Alberta, who also writes about his experience with casinos. He’s been in the business for over 10 years, following the ever-changing industry landscape. His articles are aimed at helping beginners with choosing casinos, suitable games, and strategies.
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