Slots 101: How Does RNG Work?

How RNG Works in Slots (And Why It Matters)

Have you ever wondered what actually happens the moment you hit Spin on your favourite online slot?

You may be surprised to know that there's not a little clapping monkey hidden away in the game's code and the casino isn't secretly pulling the strings to rig the final outcome.

All those winning combos are actually powered by something called an RNG, short for Random Number Generator.

In plain ol' English, it's a complicated piece of software that decides a spin's results, making sure everything stays random and fair. 

If you're confused about RNGs and want to know more about how they work and why they're so important, keep reading.

What is an RNG?

RNG stands for Random Number Generator and they've been around since the mid 1990s, even before the days of dial-up internet.

Without getting too technical, RNGs are a complex computer algorithm programmed into every online slot's code, generating thousands of random number combinations every second. 

The numbers relate to specific symbols or reel positions, creating a random outcome from the moment a player presses the Spin button, sealing their fate. 

How RNGs Work in Slots

1. The RNG generates a unique sequence of numbers within milliseconds.
2. That sequence corresponds to specific symbols and reel positions.
3. The reels stop according to that outcome, which you see on screen.
4. The system checks if that combination triggers a payout or feature, and voilà, your result is displayed.

Each second, even when a game is not active, RNGs will continue generating sequences with thousands of numbers. 

To determine outcomes, RNGs rely on a seed value (the initial number input into the system) and the algorithm to create an unpredictable result, so what you see is what you get.

Can You Predict RNG Outcomes? 

People love to claim that there's a method to the madness of spinning, saying that slots are “overdue” to pay out or if it's going through a cold streak, it's bound to “run hot” soon enough. 

However, these are complete slot myths, as slot players are often a superstitious bunch. 

With RNGs, every spin is completely independent of the last, meaning that even if you've got a crystal ball, it's virtually impossible to predict each result. 

RNG technology is also embedded within a slot's code cryptographically, making it impossible to be tampered with. 

All this to say, no, you can't outwit RNGs, and there's no “optimal” time to play slots either.

RNGs in slots don't care if it's 3am on a Saturday, payday, or if Mercury's in retrograde. The outcome will always be the same: 100% random. 

How are RNGs Tested and Certified? 

Rules and regulations put into place by licensing bodies like the UK Gambling Commission require (by law!) that online casinos must have their games tested for fairness to ensure there's nothing sus going on behind the scenes. 

That's where independent auditers like eCOGRA come in, verifying that each RNG produces random results and cannot be rigged by either players or operators. 

This third-parting testing enables players to trust that all spins are operating fairly, even if luck isn't on their side.

You can check if a casino is eCOGRA-verified by checking the footer of the site where their logo will be displayed. 

RNG vs RTP

If you've ever fallen down a rabbit hole about the science of slots, you've probably seen these two terms thrown around — RNG and RTP. 

While they may sound confusingly similar, they aren't the same. 

• RNG: Decides what happens on every spin.
• RTP: The Return to Player rate, which is the long-term average payout a slot theoretically pays back over time.

The RTP of a slot is usually displayed as a percentage (sometimes listed in the game's paytable) with most games sitting between 95% and 98% RTP. Anything over 96% is generally considered to be a good pick. 

In short, RNG decides what happens and the RTP predicts (roughly) how much is paid back to players over time. 

Final Thoughts

Basically, RNGs are what keep slots fair and functional. Without them, every spin on a slot would be complete chaos and people would be straight on Trustpilot to complain about rigged results.

Every spin will always be random — no matter what rituals, lucky charms, or betting patterns you try.

Understanding how RNGs work help players see slots for what they are: a form of entertainment, and not a reliable source of income.