The payout percentage is usually determined by the RTP figure. It stands for Return to Player and gives you a rough idea about the money that comes back to players from the company. However, this is not a face value figure as winnings are purely based on luck or random selection. For example, if 100 users deposit money and wager for a game, only 1 or 2 players might win. Even then, the share of winnings between them will be disparate as it will depend on several other factors too.