How Slot Machine Reels Work: Number of Symbols Explained

Slot machines might look simple on the surface, but there’s a lot happening behind those spinning reels. For many people, how symbols move and line up can feel a bit mysterious.

Whether you’re playing in a local arcade or scrolling through an online site, the number of symbols on each reel shapes how a game behaves, and not all slots are built the same.

Here’s a clear look at how reels and symbols really work, without complicated jargon. Games are designed in different ways, and understanding that design could change how you read what’s on screen. All of this sits within standards set by the UK Gambling Commission (UKGC), which exist to keep outcomes fair. Read on to learn more. 

What Determines How Many Symbols Are On A Slot Machine Reel?

The number of symbols on a slot reel is mainly a design choice. Traditional machines you might find in a pub or arcade usually use a set number per reel, often somewhere between 10 and 20.

Online slots aren’t limited by physical parts, so developers can build reels with more or fewer symbols and add features like expanding reels, extra rows, or special symbols that appear in different ways from one spin to the next. The mechanics can vary a lot from one game to another.

The mix of symbols and how they’re arranged influences how often certain combinations can appear, but each spin is independent. There isn’t a single “right” amount of symbols; some games keep things simple, while others pack in special features for variety.

If you do decide to try your hand at slot games, remember to do so responsibly and within your means; never wager more than you can afford to lose.

Physical Reels vs Digital Reels: What’s The Difference?

Physical machines use mechanical reels that stop on fixed positions. Each reel carries a set list of symbols, commonly between 20 and 25, and the outcome depends on where those reels come to rest. Because the reels are physical, there’s a natural limit on how many symbols and combinations can exist.

Digital slots use virtual reels controlled by software. What you see on screen is a visual display of the result chosen by the game’s system. With no physical constraints, these games can introduce extra rows, changing reel heights, bonus rounds, cascading reels, and large “ways to win” formats.

How Do Random Number Generators Affect Reel Symbols?

Random Number Generators, or RNGs, produce number sequences that the game maps to reel positions. The software constantly cycles through thousands of values every second. When you press spin, it takes a snapshot and translates it into the symbols you see.

Two spins may look similar, but they’re picked independently. The reels on screen are just the animation of a result already chosen by the system at that moment. This is why there’s no pattern to follow and no build-up from previous spins.

RNGs used in licensed online slots are tested and certified under UK rules to make sure outcomes are fair and unpredictable. You can choose any theme or feature set you like; the randomness behind each result is the same.

Why Do Some Slots Have More Symbols Than Others?

It mostly comes down to design goals. A straightforward slot might use a smaller set of symbols to keep things clear and familiar. A more feature-heavy game might include a larger pool to support wilds, scatters, expanding symbols, bonus triggers, and different prize tiers.

More symbols allow for more possible outcomes on each reel, which opens the door to varied mechanics. For example, formats like Megaways can change the number of symbols shown on a spin and create tens of thousands of potential ways to line up wins. None of this is about the presentation alone; it’s about how the game is structured under the hood.

Does The Number Of Symbols Influence Slot Volatility?

Symbol count can influence volatility, but it’s one piece of a wider design. Volatility describes how a game spreads out its wins. Some games pay smaller amounts more frequently, while others pay less often but may include higher prizes within their prize table.

A slot with a wider set of symbols and complex features can create more possible combinations. That variety often pairs with less frequent regular wins, balanced by the potential for bigger outcomes when features do connect. By contrast, games with fewer symbols and simpler setups may cycle through familiar combinations more often, which can feel steadier.

Developers balance symbol counts with prize sizes, features, paylines or ways-to-win, and the overall Return To Player (RTP). RTP is a theoretical percentage calculated over very large sample sizes; short sessions can look quite different from that figure.

Can The Number Of Reel Symbols Affect Your Odds?

The number of symbols on each reel is one factor in how likely particular combinations are. Fewer symbols mean fewer total outcomes; more symbols mean far more possible outcomes. It’s similar to the difference between flipping a coin and rolling a die: the more faces, the more ways things can land.

As explained earlier, certified RNGs make every spin independent. That means there’s no memory between spins, and no change in probability based on what just happened. Symbol counts and their arrangement shape the mathematical model, but they do not create any advantage for a player on a single spin.

If you want to see exactly how a specific game is set up, the info or rules screen usually lists reel layout, features, and RTP so you can understand the structure before you consider playing.

Discover Online Slot Games at Slotzo

If you’d like to explore online slots, Slotzo brings together quick, classic three-reel titles and more detailed video slots with features like cascading reels and Megaways, where the number of ways to win can climb into the hundreds of thousands.

At Slotzo, it’s simple to browse by theme, mechanics, or features. Each game has a details page showing volatility, paylines or ways, and the RTP figure, which is a theoretical average calculated over many spins. 

We operate under a UKGC licence, and our games use certified RNGs. Account tools are available if you want to set time or deposit limits. Ready to put this knowledge into context? Feel free to explore our library and see how reel symbols, features, and design choices play out across different games, all in one place. Always keep responsible gambling practices in mind.

_{**The information provided in this blog is intended for educational purposes and should not be construed as betting advice or a guarantee of success. Always gamble responsibly.}

_{*All values (Bet Levels, Maximum Wins etc.) mentioned in relation to these slot games are subject to change at any time. Game features mentioned may not be available in some jurisdictions.}