Fairness of Casino Games → Provably Fair or Rigged?

Many players think that casino games have been rigged to the benefit of the gambling hall. While there are cases where that did occur, it's the exception to the rule. Governments entitle testing bodies and gambling commission to oversee all legal online casino operators, who then ensure that those are acting within the boundaries of legallity.

How casino payout mechanics work

Game developers integrate a mechanic called return-to-player (RTP) into every casino game they create, which is the payout algorithm that defines how much of a player’s bet returns on average to them.

Casino games have different payout rates depending on their category, e.g. baccarat typically has a higher RTP than slots.

For example, a video slot might have an RTP of 95% – which means 5% of your bets are the average profit the casino is making off your bet, and 95% returns to you.

However, you won’t lose 5% of your bet every single time as variance affects outcomes.

If you wager £2,000 pounds and win £2,000, the actual RTP for that sample size would be 200%.

But it can go the other way too, which is when players start questioning the integrity of the casino.

The problem here is that the practical RTP deviates from the theoretical RTP due to variance and the inherent volatility of casino games.

Theoretical RTP

Game developers first create the payout algorithm defining win frequencies and the return-to-player rate.

They then simulate millions of game circles to test whether their code is functional and pays out according to the return-to-player rate they designed. 

They then assign the tested theoretical RTP to the casino game and send the testing data and software to gambling commissions who inspect both for flaws.

Once the game is proved faultless, the software provider can distribute their new games to online casinos.

Actual RTP

The online casino tracks how much players bet and win on each casino game and then must send this data to gambling commissions who review whether the actual RTP which is derived from those figures deviates from the theoretical RTP.

You can calculate the actual RTP by dividing turnover and win figures.

For example, if players bet £1,000,000 and the game pays out £900,000, the actual RTP would be 90%.


The gambling commissions compare the actual RTP to the theoretical RTP and would remove the operator’s license if the numbers deviate too much from the thresholds they set.

For example, the actual RTP should be within a 3.4709% proximity of the theoretical RTP after 100,000 bets, and if it’s not, the game is likely faulty and will be qued for further review.

If further tests indicate that the two RTPs diverge too much, the online casino likely loses its license as it would mathematically prove that they fixed the game.

Win frequency (volatility)

Every casino game has one of three volatility levels which influence how often players win.

  • Low – you win small prizes very frequently 
  • Medium – you win less frequently but bigger prizes
  • High – you’ll win even less frequently but much bigger prizes

Your play style can also affect the volatility of payouts.

For example, if you bet on red on roulette, you have a chance of 47.4% winning double your stakes.

But if you bet on the number 17 for example, you have a chance of 2.6% winning 36x your bet.


Whether you wager money on roulette, slots, blackjack, bingo, poker, baccarat or any other game of chance, as long as you play at a licensed online casino or gambling hall, the outcomes are provably fair, as attested by independent testing houses like eCOGRA.

In the unlucky case you are actually playing rigged games, you most likely play at an unregulated online casino – which is not reviewed by independent testing houses – or one that is soon to be unregulated as it will lose its license.

That is why it’s important to choose your online casinos from a reputable comparison website that only lists regulated operators, like Gamblee.

Unlicensed operators are not only likely to rig their games, but they are also known to:

  • confiscate winnings for the wrong reasons
  • pirate games and fix the RTP
  • don’t pay big wins or jackpots
  • stall withdrawals

You are just (extremely) unlucky and experience the negative aspects of variance if you suspect that the casino rigs their games because most likely they do not.