The RTP is always referred to as a percentage and the actual figure varies from game to game. The actual figure can be part of the publicity drive for a new game with hopes that a 97% RTP will persuade players to start using the game.
As you might expect this is a very complicated calculation. There are several factors that have to be taken into consideration. These includes the payouts and probabilities of every single outcome that can happen in the game. As games grow larger and larger with some such as ‘Miss White’ offering over 1000 different ways to win, you’re going to be spending a fair amount of time working out the RTP.
To try and explain just how this calculation works it’s easier to consider a simpler game. Say it’s one that has only ten possible outcomes and these are all equally likely to happen. If you gamble one coin and over a period of ten spins you win nine coins, then the RTP will be 90% as you would have staked a total of ten coins and won nine (9/10). Of course that is a really simple calculation but that the basis on which an RTP is calculated. If a game does have a 90% RTP then this means the house has a 10% house advantage.
Sadly, it doesn’t work that way because of the random way in which the game works. That RTP figure will be achieved over time but it’s more a case of the calculation being made over the long-run rather than how you get on when playing the game for half an hour.