How do slot machines work — answered without the sales pitch

Random numbers behind every spin

Every spin begins with a random number generator, a program that keeps producing numbers whether or not anyone is playing. When you press the button, the machine takes the next number in the sequence and maps it onto a set of reel positions. That mapping is what you see stop on the screen. There is no memory of your last spin and no cycle that must pay out before it can move on; each result is drawn independently.

Because the result is fixed at the moment the spin is triggered, the symbols you see chasing each other on the reels are presentation, not a near miss you can react to. The machine has already decided where each reel will stop. Nothing about your timing, your bet size or how long you have been playing changes that mapping.

In plain terms:Random number generator

A random number generator is the program inside a pokie that produces the numbers used to decide where the reels stop. It runs constantly and independently, so each spin's outcome is unrelated to the one before it.

Lines, reels and symbol combinations

A payline is a path across the reels, and a win is usually a set number of matching symbols landing on that path from the leftmost reel onwards. Older pokies had a single line across the middle; modern ones can have many, and Megaways games change the number of symbols on each reel from spin to spin rather than using a fixed set of lines. The number of lines does not make a game more or less likely to pay overall — it changes how wins are distributed and what a spin costs if you cover every line.

Scatters and bonus symbols often ignore paylines entirely. A scatter may pay wherever it lands, and a set number of them can trigger free spins or a feature. That is why two pokies with similar-looking reels can behave very differently: the rules that decide which combinations pay are set in the game's maths, not in the artwork.

RTP, volatility and what they mean

Return to player, or RTP, is the long-run average percentage of all money wagered that a game is designed to return to players over millions of spins. It is not a target for your session. A game with an RTP of 96.79% can take far more than that from you in an hour and can also pay far more; the figure only settles over a volume of play no individual will ever reach.

Volatility describes how a game delivers its returns. Low-volatility games tend to produce smaller, more frequent wins; high-volatility games can go long stretches without a meaningful payout and then land a large one. Neither is better or worse in itself. They suit different bankrolls and different tolerance for sitting through dry spells, and the maximum win figure is the top of the range, not an expectation.

What the published numbers put in front

The shortlist on this page shows how RTP, volatility, maximum win and line count differ between games.

What else people ask