Just like every single casino game on the planet, slots have their own house edge, or house advantage. The house edge is the expected average loss to bets placed, and although the amount is different in all casino games...all casino games, both in land based casinos and in online casinos will have one. With online slots it’s a little different in that each slot will have it’s own house edge, and all online slots will have a payout percentage, and it’s this that will determine both the house edge, and your expected payout from any given slot.
The payout percentage on all online slots is governed by the RNG or the Random Number Generator, which is a part of the programming of the slot that determines which symbols arrive on the reels and therefore how much, and when the slot pays out. The payout percentage therefore is driven by the RNG, and you may be surprised at the amount of variance there is between one online slot and another.
Online slots are designed so that they payout between a certain percentage of the money that is wagered on them, and this can range from a lowly 88% all the way up to over 98%, meaning that one slot may have a very different expected payout to another. However we’ll state right now that you cannot expect to place $10 in wagers on a 98% payout slot and get $9.80 back...it doesn’t work quite like that, as that payout percentage is set for the lifetime of the slot. This means that over a given period of time, a slot with a 98% payout percentage will pay that amount back but you may not be the lucky player that gets the benefit of this. To put it another way, that same $10 wagered on a 98% payout slot may give you a win of $200, and as you can easily see, that’s way over the 98% payout mark. However at some stage over a period of time, that machine will eventually payout the percentage that the RNG has determined.
This all means that yes, payout percentages do matter when playing online slots, as the higher the percentage number, the better chance you have of winning, however as everything is managed by the Random Number Generator, you have no real idea when any slot will pay out the big bucks, meaning that, at the end of the day, it’s all down to luck.