RNG & RTP Auditing

Otherwise known as a random number generator (RNG), an RNG is the reason all online casino games are fair.

Sharon McFarlane
May 31 2021

Otherwise known as a random number generator (RNG), an RNG is the reason all online casino games are fair. Because a computer can’t “shuffle” a deck of cards, choose a random ball or stop a set of reels at random, we need technology. To this end, computer algorithms defined by complex mathematical formulas are programmed into all online casino games. These algorithms process dozens of variables and calculate thousands of outcomes in order to come up with a fair result.

According to iTech Labs, one of the leading RNG testing agencies in the world, a correctly functioning system ensures that…
cards, die numbers, slot game symbols, feature game outputs, jackpot triggers, etc. are statistically random and unpredictable.”

Given that computer code can be examined and tested for faults, it follows that RNGs can be tested. To comply with the licensing conditions outlined by agencies such as the UK Gambling Commission (UKGC), all operators must have a valid test certificate. In other words, all licensed sites must prove that their games are fair by allowing a third-party to test their RNG.

How RNGs Are Tested

In theory, RNGs are great. By using powerful algorithms to determine the outcome of each betting round, everything you play is guaranteed to be random and therefore fair. However, if a program isn’t functioning properly, the randomisation process can be compromised. To ensure this doesn’t happen, testing agencies carry out in-depth tests that look at things such as:

Statistical Randomness: Are the results recorded statistically random? I.e. are they distributed in such a way where there isn’t any bias towards a certain number/s.

Internal State of an RNG: Is the RNG’s computer code clean and free of errors.

Seeding and Reseeding: Seeding refers to the number used to start a random sequence. Tests will look at how a seed is generated and whether it’s a random process.

Un-repeatability: Can a sequence of results be replicated? If so, the system isn’t fair. A properly functioning RNG won’t have any identifiable patterns.

Auditing Games: RTP vs. RNG

What’s important to note is that different games are tested in different ways. All casino games (i.e. blackjack, roulette and baccarat) and video slots are tested by conducting an RTP audit. In simple terms, RTP (return to player) refers to how often a player can expect to win in the long run (i.e. millions of betting rounds). For example, a game like blackjack might have an RTP of 97.80%. In theory, this means you can expect to get back £97.80 for every £100 you wager.

For every casino game, there is a predetermined RTP. In other words, there is an expected minimum return rate if all things are fair. During an RTP audit, agencies take millions of game logs (results) and look at the total bets vs. total money won. Factoring these two variables into an equation, analysts can establish whether or not a game’s payout rate is in line with theoretical expectations.

When it comes to multiplayer games such as poker, dice and bingo, an RNG audit is used. During these tests, game logs showing details of shuffled cards, dice rolls or bingo number distributions are extracted. From this information, analysts can test the logs and determine how likely an event is to happen. For example, if a poker game is being analysed, the agency can see how likely a flush, full house, straight etc is likely to occur. These results can then be compared to the theoretical probabilities of said events happening. As long as the results are within the right range, the game is considered fair.

RNG Auditing Companies and Certificates

It’s important to note that operators aren’t mandated to use a certain testing agency. They do, however, have to prove their games are fair and there are a handful of companies that are recognised as reputable and they include:

  • eCOGRA
  • Gaming Laboratories International (GLI)
  • Technical Systems Testing (TST)
  • iTech Labs
  • NMi (Czech focused agency)
  • PWC

Each of the above agencies are recognised independent bodies. This means they have working relationships with iGaming regulators and operators, but they are completely separate. Any casino that wants a licence from the UKGC et al will have to pay one of the testing companies for their services. Because of this, you can scroll down to the bottom of any of our recommended online casino, poker and bingo sites and look for two things.

1. Certificate of Fairness: Companies such as eCOGRA provide operators with a logo and hot link to their results. For example, if you look at one of our community favourites, 32Red Casino, you’ll see it has the eCOGRA logo at the bottom of the homepage. From here, you can click the link and see the company’s latest test results. 

32Red eCogra


2. A Regulator’s Logo: If you’re in the UK, the UKGC’S mark is what you need to look for. When you find this, you can be confident that the site has a fair system because this regulator won’t licence a site that doesn’t offer provably fair games.

Live Dealer Games and RNGs

Any casino with a certified RNG is fair and safe. However, in recent years, live dealer games have become increasingly popular and they don’t use RNGs. The reason for this is that everything happens in front of you. Just as you’ll see the dealer shuffle the cards or spin the roulette wheel in a real casino, the same is true of live games online.

But couldn’t a casino use camera trickery? No. Every live dealer table features something known as RFID trackers. These infrared microchips do two things. In the first instance, they track the action so it can be linked to the virtual overlay that you’ll see on your computer screen. Secondly, the RFID chips keep tabs on the results and log them in a database. This allows operators to keep track of their wins/losses and ensure the results are fair.

These results are audited on a regular basis and this, in turn, means you can be confident that none of the dealers are manipulating the game. In short, if you’re playing live or virtual games at any of our recommended sites, you can be confident that everything is on the level.

Reviewer Photo
Written by: Sharon McFarlane
May 31 2021
creating content within the iGaming sector for over 11 years. Throughout that time she has worked with blue-chip operators and affiliates to create objective and unbiased copy that would add value to the user