RNGs and Fairness: How Online Casinos Keep Games Random

You want to play fair casino games to feel safe when handing over your money. The RNG is the fairest tool there is. It ensures that each roll of the dice, turn of a card, or spin of a reel is totally random. What is an RNG and how does it work? Who verifies its accuracy? How does RTP come into play? How can you check if a casino game is fair? What does “provably fair” mean in a crypto game? We have a quick list to run through and some safe resources to lab and authority sites. Read through before you part with your cash.

What is an RNG in online gambling?

What is an RNG? An RNG is a random result generator. In a slot machine it determines where each reel will stop. In a video table game, it determines what the next card or roll of the dice will be. Each hand is an independent event. It does not take into account what happened previously. It does not go “cold” or “hot”.

It is also worth noting that live dealer games are something different altogether. There is a human dealer determining where the cards or wheel stops. They do not use an RNG to determine the outcome. They use cameras and a physical wheel. However, the studio and devices are tested and regulated as well.

Fair does not mean frequent payouts. It means the game is not rigged. You still face the house advantage, which we explain below.

How casino RNGs work (PRNG vs hardware RNG)

A lot of games on the internet use a PRNG. PRNG stands for pseudo random number generator. It’s a mathematical software. It takes a secret input, called a seed. And then applies a robust formula to the seed to generate an apparently random sequence of digits. A good PRNG is fast, passes a lot of tests and is resistant to attacks from those who try to guess its output.\nBut where does the seed come from? A casino or a game company collect “entropy”. This is some noisy data from, for example, the time of day, mouse movement, keyboard typing or special hardware. It’s trying to generate a seed from an unpredictable source. Then the PRNG is run to generate some random numbers for each round of a game.

In some cases there is also a hardware RNG (HRNG), which is a device that captures some physical randomness (electrical noise, etc.). These are true RNGs. HRNGs are slower, and it's harder to test them in the same way every time, so most online games use "cryptographically secure" PRNGs. That is, they are designed to be secure against attempted breakage, and they must go through rigorous testing. You can find more information about required randomness properties in the IETF standard, here: RFC 4086, and in the NIST guidelines, here: NIST Random Bit Generation.

Why PRNGs? They're fast, deterministic and you can test them with the same seeds. In a lab, you can replay the same test over and over again. That's great for audits. You can also keep track of versions. which prevents cheating and mistakes.

Why PRNGs? They are fast, stable, and easy to test with the same inputs. Labs can repeat tests. That is good for audits. It is also easy to track version changes. This helps stop cheats and errors.

Who tests the RNGs? Labs, standards, and certificates

Independent test labs check casino games. They test the RNG, the game math, and the code. They run many rounds to see if the output is random and unbiased. They also check how updates are done and logged. Here are well-known labs:

eCOGRA: ecogra.org (see seal search: seal.ecogra.org)
GLI (Gaming Laboratories International): gaminglabs.com
iTech Labs: itechlabs.com (certificates: itechlabs.com/certificates/)
BMM Testlabs: bmm.com
QUINEL: quinel.com (certificates: quinel.com/certificates/)

It means there’s a regulatory body that monitors the industry, licenses labs, and requires standards to be met.

UK Gambling Commission (UKGC): gamblingcommission.gov.uk
Malta Gaming Authority (MGA): mga.org.mt
New Jersey Division of Gaming Enforcement (NJ DGE): njoag.gov
iGaming Ontario / AGCO: iGamingOntario.ca and agco.ca
Gibraltar Gambling Commissioner: gibraltar.gov.gi
Isle of Man Gambling Supervision Commission: gamblingcommission.im

What do labs and regulators check?

RNG output is random and unbiased over time.
Game math matches the stated rules and RTP.
Version control, change logs, and access control are in place.
Ongoing checks happen after launch, not just once.

How to verify a certificate: first, find a lab seal or link in the casino footer. Click it. Check if it opens a live page on the lab site. Make sure the casino or game provider name matches. Check the game list and version numbers. If in doubt, search the lab’s public database for the brand name. If there is no lab page, be careful.

RNG vs RTP vs volatility vs house edge

These words can look the same. They are not. Here is a simple way to see the difference:

RNG fairness: makes every result random and not biased.
RTP (Return to Player): the long-term average payback, like 96%. In the short run, your result can be far from this. See UKGC’s guide on RTP here: UKGC: What is RTP?
Volatility: how “swingy” the game is. High volatility means long dry spells but big hits at times.
House edge: the casino’s built-in profit over many rounds.

They are not.

Common myths, debunked

“The casino tightens payouts after a win.” False. The RNG has no memory. Each round starts fresh. Labs test this. Change management stops secret tweaks. Regulators can punish fraud.
“Slots pay better at night.” False. Time of day does not affect the RNG.
“If I bet more, the RNG gives me a win.” False. Bet size does not change the random result.
“I can track a pattern and beat the RNG.” False. Good RNGs are built to stop patterns you can use.

How to check fairness yourself (step-by-step)

Use this quick checklist before you play:

Check the license. Look for UKGC, MGA, NJ DGE, AGCO/iGaming Ontario, Gibraltar, or Isle of Man. Click the logo and confirm on the regulator site. For UK, search the brand on UKGC Public Register. For NJ, use the NJ DGE site above.
Find the lab certificate. In the footer, look for eCOGRA, GLI, iTech Labs, BMM, or QUINEL. Click the seal and confirm it opens on the lab domain, not just a picture.
Match details. Check that the operator name, game provider names, and version numbers match the games you see on site.
Confirm RTP. Many regulators want RTP info in the game help screen or site help. Compare the RTP shown in-game with the provider page if public. UKGC explains RTP rules here: Display of RTP.
Test in demo. Play the demo. Check if the rules match what the help screen says. A demo is not proof, but it helps you spot mistakes.
Check provider names. Big names tend to follow strict rules. Confirm the provider has lab certs (many list them).
Read the T&Cs. Make sure bonus rules do not block cashouts for strange reasons.
Red flags: no license link, no lab seal, only images (no live lab page), claims like “100% payout,” or pressure to deposit fast.

Provably fair systems in crypto casinos

Here’s a handy pre-game checklist:

Before the round, the server makes a secret “server seed.” It shows you a hash of that seed. A hash is like a one-way fingerprint.
You can set a “client seed” yourself. This adds your own input.
A “nonce” is a number that goes up by one every round.
After the round, the site lets you see the server seed. You can run a check to see if the hash matches and if the result came from the seeds and nonce. This proves they did not change the seed after the fact.

This helps you confirm fairness in supported games. But remember: house edge still applies. Also, provably fair systems vary. Read the site’s guide. If the code is open source, that is a plus. If not, ask for a clear method page. For general crypto fairness ideas, see NIST randomness guidance again: NIST.

How audits and controls stop cheating

You can verify every round once you play.

Source code control: only approved staff can change the game.
Change logs: every change is recorded and reviewed.
Separation of duties: the person who writes code is not the one who approves it for live use.
Build checks: the lab often tests the exact build that goes live.
Post-launch monitoring: regulators can do spot checks and pull logs.

These steps make secret “switches” or “rig modes” very risky and easy to detect. Labs and regulators can suspend or revoke licenses. This is why choosing a strong license matters.

Choosing reputable casinos you can trust

Here is a simple rule: strong license, trusted labs, clear RTP, and good support. Look for:

A top-tier license (UKGC, MGA, NJ DGE, AGCO/iGaming Ontario, Gibraltar, Isle of Man).
Live lab pages from eCOGRA, GLI, iTech Labs, BMM, or QUINEL.
Game providers you know, with public info on their math and audits.
Responsible gambling tools: deposit limits, time-outs, and self-exclusion.
Fast, fair complaint handling and clear T&Cs.

If you want a shortcut, you can review vetted lists and methods here: https://usonlinecasinos.biz/" rel="noopener">https://usonlinecasinos.biz/. There you can compare license status, lab seals, RTP visibility, and support quality in one place.

Responsible gambling and legal notes

Labs can lose licenses, and so can regulators.

Which is why license strength is an important consideration when selecting one.

BeGambleAware (UK): begambleaware.org
National Council on Problem Gambling (US): ncpgambling.org
Gamblers Anonymous (global): gamblersanonymous.org

The rule of thumb is this: Good license, reputable labs, simple RTP, and decent support.

FAQs

Are online casino games rigged?

You can get a shortcut by checking verified lists and guides at https://usonlinecasinos.biz/. This way, you can easily find the license status, lab stamps, RTP information, and support levels of all your chosen sites.

What is a random number generator in slots?

Please only gamble if it is legal in your jurisdiction and you are over 18 (or 21 in some areas). Do not gamble to earn money. Only gamble responsibly and within your limits. Do not gamble for extended periods. Do not feel pressure. Stop if it’s a problem and seek help

How do I know a casino’s RNG is fair?

Confirm the license on the regulator site. Open the lab seal in the footer and check it on the lab domain. Match the brand and game versions. If you cannot verify, do not deposit.

What is the difference between RNG and RTP?

RNG makes results random and unbiased. RTP is the long-term average payback. A fair RNG does not change the RTP. It just makes sure the game follows the math in a random way.

Do live dealer games use RNGs?

In a licensed jurisdiction, with a reputable lab certifying the software, the games are not rigged.

Who are the best regulators and labs to look for?

The regulator is testing the operator.

How does “provably fair” work?

Always verify both.

Can I increase my chances in RNG games?

An RNG is a computer program that selects the stopping positions for the reels.

Conclusion

It doesn't keep track of previous results.