Slot machines are typically programmed to pay out as winnings 0% to 99% of the money that is wagered by players. This is known as the "theoretical payout percentage" or RTP, "return to player". The minimum theoretical payout percentage varies among jurisdictions and is typically established by law or regulation.
To find the payout percentage on a slot machine, you can look for information provided by the casino or the game manufacturer. In many jurisdictions, casinos are required to display the payout percentage for each slot machine.