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Slot rules

How Online Slots Work: RNG, Independent Spins and Random Outcomes

Last checked: 4 min read By SlotConfig Editorial Team

Two identical slot machines showing different symbol arrangements

An online slot decides each spin with a random number generator (RNG): when you press spin, the game takes a random result and shows it as symbols on the reels. Each spin is independent of the ones before it, so a slot is never “due” to pay after a losing streak, and stopping or starting at a particular moment does not change your chances. What the game designer controls is the long-run return, the RTP, through the paytable and the probability of each outcome. In Ontario, the AGCO’s standards require every game and RNG to be approved by the Registrar or certified by an AGCO-registered independent testing laboratory before it is offered, and they limit how fast and how automatically you can play.

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What does the random number generator do?

It produces the result of each spin. The reels you see are a display of that result, not a mechanical process. The game’s design sets the probabilities: how often each symbol combination comes up and what it pays. Put together over a very large number of spins, those probabilities produce the game’s RTP, the share of stakes it pays back.

That is why one game can exist in several versions. A provider can set a title to return different percentages, and the casino runs one of them. On October 19 and 20, 2026, Gates of Olympus showed 96.50% at bet365 in Ontario, the same as Pragmatic Play’s own page, and 94.5% at Betty in Ontario. The reels, symbols and features look the same; the probabilities behind them are set differently.

What does “independent spins” mean for you?

Each spin starts fresh. The game does not remember that you lost the last twenty spins, and it does not hold back a win after a big payout. Three practical consequences:

  • No slot is “due”. A long losing run does not make the next spin more likely to win.
  • Timing does not matter. When you press spin, or whether you stop the reels, does not change the result.
  • Streaks are normal. Random results cluster. You will see runs of losses and runs of small wins, and neither predicts what comes next.

A short calculation shows why streaks feel longer than they should. Suppose a game’s rules said a feature triggered on average once in 200 spins. The chance of going 200 spins without it is (199/200) to the power of 200, about 37%. More than one session in three would reach the “average” without seeing the feature once, and nothing would be wrong with the game.

Why do the rules limit how fast you play?

Speed multiplies cost. Ontario’s AGCO standards ban autoplay, ban playing several slots at once, require at least 2.5 seconds between game starts and rule out turbo, quick-spin and slam-stop features. At that minimum interval, play is capped at 1,440 spins an hour. At a 96% RTP and C$0.50 a spin, an hour at full pace means up to C$720 wagered and about C$29 of expected cost.

The same standards require slots to show your session net position in Canadian dollars and forbid presenting a return equal to or below your stake as a win. Both rules keep the real result on screen when the animations suggest otherwise.

What does the RTP tell you about the RNG?

RTP is the long-run result of the RNG and the paytable together. It does not describe a session. Of the 289 OLG.ca slot pages we collected, all showed an RTP and 73 showed a range rather than one number, from 86.0% to 90.5% at the low end to 96.73% to 96.95% at the top. OLG.ca does not explain what the ranges depend on. Our explainer on what RTP does and does not tell you covers how to use the figure.

What about volatility?

Volatility describes how the RTP is paid out: in many small wins or a few large ones. Two games with the same RTP can have very different volatility. Some casinos show it: bet365’s Ontario lobby panel lists a volatility label next to the RTP and the number of reels. Higher volatility means longer losing runs between larger wins, which can matter as much for your budget as a small difference in RTP.

Do near misses mean a win is close?

No. A near miss, such as two bonus symbols landing with the third just above the window, is one random result among many, shown on the reels. Under independent spins it says nothing about the next result. However often near misses appear, they are not a signal that a win is getting closer.

Who checks that the RNG is random?

In Ontario, the AGCO’s standards require games and random number generators to be approved by the Registrar or certified by an AGCO-registered independent testing laboratory before they are offered on any gaming site. The rules or help pages must also give accurate information on odds, payouts or returns before a bet. Outside regulated markets, what is tested and by whom depends on the regulator behind the site.

What we could not confirm

  • Which testing laboratories certified particular games on Ontario sites: game pages do not name them.
  • The probabilities behind individual games: providers publish the RTP, not the full table.

Put it to use

Before a session, read the game’s RTP and, if shown, its volatility. Decide your stake and a stopping point in advance, and set them as limits in your account. During play, ignore patterns and “near misses”; judge the session only by the net position on screen. Our guide to reading the paytable and setting the stake covers the practical steps.

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Sources

  1. AGCO: Registrar's Standards for Internet Gaming
  2. OLG.ca: slot game pages
  3. Pragmatic Play: Gates of Olympus game page
  4. Betty: Gates of Olympus game page
  5. bet365 Ontario casino: game info panels

More in this guide

Guide overview: Slot rules →