Understanding RNG: How Casinos Keep Games Random

Last updated: [current date]. This guide is meant to be simple. We use simple words to explain complex concepts. And we provide links to credible resources so you can verify anything.

Quick answer: What is an RNG in casinos?

A casino RNG (Random Number Generator) is a machine that generates a new, random number, many times per second. The game selects a number to determine the outcome, such as the symbols you see on the reels, or the next card in a shuffled deck. Each spin or hand is an independent event. The outcome of previous hands or spins does not affect future outcomes. RNGs used in licensed casinos are regularly audited and verified by third-party testing houses.

tl;dr: The RNG ensures that games are truly random and unpredictable. It does not determine who wins today. It merely selects outcomes that nobody knows in advance.

Why RNG matters: fairness, trust, and rules

That’s where randomness helps both you and the casino. It ensures you have an equal opportunity to win with each spin of the wheel or roll of the dice, and it ensures the math behind the games remains constant over time. Keep in mind, “equal opportunity to win” doesn’t mean “50-50.” There is almost always some level of house advantage built into casino games, but that is part of the game itself, not the RNG.\nAnd there are good regulators that make rules about RNG and ensure the casinos and game developers comply. In the UK, for instance, the UK Gambling Commission requires RNG certification. The same goes for Malta’s Gaming Authority and the DGE in New Jersey. In Ontario, there are technical standards set out in the AGCO iGaming Standards.

Good regulators make RNG rules and check that casinos and game makers follow them. For example, the UK Gambling Commission (UKGC), the Malta Gaming Authority (MGA), and the New Jersey Division of Gaming Enforcement (DGE) all require certified RNGs. In Ontario, the AGCO iGaming Standards set clear technical rules.

How casino RNGs work (PRNG vs TRNG)

There are two main types:

• PRNG (Pseudo-Random Number Generator): This is a smart algorithm in software. It uses a “seed” to start. The output looks random and is good enough for games if done right. Most online casino games use PRNGs.
• TRNG (True Random Number Generator): This is hardware that reads noise from the real world, like tiny electronic signals. It is “true” randomness, but harder to run at scale online.

These are designed to prevent predictability and tampering.

Seeding and entropy

The seed is a starting value for a PRNG. If the seed is strong and secret, the output is safe. Good systems use many sources of entropy (random inputs) to make a seed. They also rotate seeds on a schedule. This lowers the risk that anyone can guess the next number. If you want to read more on safe random numbers, see the OWASP guide to random number generation.

From number to outcome

The RNG gives a number. The game maps that number to an outcome. For a slot, that may be a stop on each reel. For a card game, it may be the index of the next card in a shuffled deck. The mapping must be unbiased, so every valid outcome has the right chance to appear. This mapping is part of the code labs review.

Who tests and certifies RNGs?

Regulators set the rules. Independent labs test the games and RNGs. Top labs include:

• Gaming Laboratories International (GLI) — known for standards like GLI-11 and GLI-19.
• eCOGRA — a well-known testing agency for online games.
• iTech Labs — tests RNGs and game math for many vendors.
• BMM Testlabs — another global testing lab for land-based and online.

They also contract out to independent labs to test the games and the RNGs.

• Source code review and build controls.
• Statistical tests for randomness (for example, tests from NIST SP 800-22, chi-square tests, and more).
• Security and change management: who can change code, how builds are signed, and audit logs.
• Re-tests after updates and regular audits.

A certificate will list the product, version, date, and scope. It shows the game and RNG passed the lab’s tests under a standard. Regulators like the UKGC Testing Strategy or the NJ DGE then oversee ongoing compliance.

RNG vs RTP vs volatility: what’s the difference?

People mix these up, but they are not the same:

Then you have ongoing monitoring by regulatory authorities such as the UKGC Testing Strategy or the NJ DGE.

Common myths and what is true

• Myth: “Casinos make slots tighter at night.”Fact: Licensed games have fixed settings. Any change needs control, lab review, and approvals. See regulator rules like the NJ Internet Gaming Technical Standards.
• Myth: “You can predict the next number.”Fact: Modern PRNGs use strong seeds and secure code. Labs test them to block practical prediction. See NIST randomness tests.
• Myth: “This machine is hot/cold.”Fact: Each spin is independent. Past streaks do not change future odds. This is the “gambler’s fallacy.”
• Myth: “Online is less fair than land-based.”Fact: Both are regulated when licensed, and both must pass lab tests and audits.

Provably fair systems in crypto casinos

The RNG is random. RTP and volatility are about game math over time. A game can be random and still have a house edge. That is normal and must be disclosed by licensed operators. For more information about player information rules, visit the UKGC and MGA sites.

• The server makes a hidden “server seed” and shows a hash of it first. The hash is a one-way fingerprint.
• You can set a “client seed.”
• Each round uses the seeds and a “nonce” (a round number) to make the result.
• After the round, you can check the seeds and hash. If they match, the casino could not change the result after the fact.

This is good for trust, but it is not a full replacement for a license, lab tests, or solid KYC/AML controls. If you want a neutral intro, see this overview of provably fair systems.

How casinos keep RNGs secure in practice

• Change control: Only certain staff can push updates. Builds are signed. Every change is logged.
• Server hardening: Systems are locked down and monitored.
• Pen tests and audits: Regular tests by third parties and by internal teams.
• Disaster and incident plans: If something goes wrong, steps are clear and quick, and regulators are told if needed.

Essentially:

How you can check fairness yourself (simple checklist)

• License first: Check the casino’s license and number on the site footer. Then check the regulator’s site to confirm it. Try the UKGC Public Register or the MGA license check tool.
• Lab logos and links: Look for lab names like eCOGRA, iTech Labs certificates, GLI, or BMM. Click through if the casino links to a live certificate page.
• Game info pages: Open the info in the game. Check the RTP, version number, and provider name. If the RTP is hidden or unclear, be careful.
• Jurisdiction: Make sure online gambling is legal where you live and you meet the age rules.
• Red flags: Avoid sites with no clear owner, no license number, or impossible promos. Read the terms.
• Mind variance: Short streaks happen. A few bad spins do not prove bias. That is just variance.

Where to find vetted casinos and reviews

If you want a short list that checks license, lab tests, RTP notes, and safer play tools, you can read independent reviews. One place to start is Uudetkasinot.biz. They list the regulator, the testing lab (if shown), and how the site handles player safety. Please note: review sites may earn a commission if you sign up. That does not change our advice to play only at legal, licensed sites.

Real examples of certificates and what they mean

A lab certificate will often include:

• Product and version: the game name and build number tested.
• Scope: what the lab checked (RNG, mapping, paytable, etc.).
• Date and lab contact: when the test was done, and who did it.

Some labs host public certificate pages (for example, see iTech Labs certificates). If a site only shows a logo image with no link, be cautious. You can also check the game studio’s site for testing info.

Responsible gambling and legal notes

• Gambling is for adults only. Check your local laws.
• Set a budget. Keep time and money limits. Do not chase losses.
• If you feel stress or loss of control, take a break and get help.

This has no influence on our decision, that you should only play at licensed sites.

This article is for information only. It is not legal advice or investment advice.

How we built this guide

We checked current rules and standards from bodies like the UKGC, MGA, NJ DGE, and GLI. We also reviewed public lab certificate pages (for example, iTech Labs) and best practices for randomness (see NIST SP 800-22). We turned the complex parts into plain words so you can make informed choices.

Key takeaways

• RNGs make each result random and independent.
• Labs test RNGs and game code. Regulators enforce rules.
• RNG is not RTP. RTP is long-term payback. Volatility is about risk and swing.
• Myths like “hot slots” are false. Each spin is new.
• Play only at legal, licensed sites. Check lab proof when you can.

FAQs

Are online slots rigged?

The above is for information purposes only and is not advice or guidance.

Can casinos control the RNG?

We looked at the latest regulations from various authorities (e.g., UKGC, MGA, NJ DGE, GLI).

How often are RNGs audited?

We translated the technical into simple English to help you make the right decisions.

Is RNG different online vs land-based?

The basics are the same: random and independent results. The hardware and setup can differ, but both must meet strong standards and pass tests.

What is the difference between RTP and RNG?

RNG is about randomness per event. RTP is the long-term average return over a huge number of plays. RNG does not force RTP in your short session.

Can I test randomness at home?

The RNG is certified and the game is tested both by independent labs and by the licensing body.

What is “provably fair” and is it better?

It’s not worth the risk.

Further reading and sources

• UKGC Remote Gambling and Software Technical Standards
• UKGC Testing Strategy
• Malta Gaming Authority
• New Jersey DGE Internet Gaming Technical Standards (PDF)
• AGCO Registrar’s Standards for Internet Gaming
• GLI Standards
• eCOGRA
• iTech Labs
• BMM Testlabs
• NIST SP 800-22: Randomness Tests
• OWASP Random Number Generation Cheat Sheet
• Provably Fair overview
• BeGambleAware | GamCare | NCPG | Gambling Therapy