Slot machines: RTP and house edge

Slot machines and their online equivalents are house-banked games with outcomes determined by a random-number process and a pay table. Unlike roulette, there is no single house-edge figure that applies to every slot. Each game, and sometimes each version or betting option inside a game, has its own mathematical return.

Theoretical return-to-player, or RTP, is the long-run share of wagers that the game is designed to return to players as a group. The house edge is the complement of that figure: if a game has a 94 percent RTP, the designed house edge is 6 percent. Those numbers are long-run averages over a very large number of plays. They are not a promise that you will receive 94 percent of your own money back in an evening.

We do not invent typical RTP percentages for “slots in general.” Published figures vary widely by game and by jurisdiction. In some licensed markets, an operator or regulator may publish theoretical RTP or related information. If you play in a licensed U.S. online casino, look for that official or in-game information rather than a blog claim.

Volatility, sometimes called variance, describes how bumpy the results can be. Two games can have a similar RTP and still feel very different: one may pay small amounts often, another may pay rarely and in larger amounts. High-volatility games can go a long time without a notable payout. That is a design feature, not a machine that is “due.”

A slot is not “ready to hit” because it has not paid recently, because a bonus symbol appeared, or because a clock or progress bar looks close to a prize. Unless the game rules expressly describe a persistent, disclosed meter, those displays can be regular parts of a random game rather than a promise. Treat jackpot marketing with the same caution: the odds of a top prize are typically very long, and the details belong in the official rules, not in a thumbnail. Each spin or paid game round is, in a properly designed random game, independent of the one before it. A long losing streak does not raise the chance that the next spin will win, and a recent win does not use up the return. Bonus rounds, free-spin features, and pick-style games are usually already included in the published theoretical RTP, not added on top of it. Licensed markets typically require games to be tested by an independent laboratory and approved by the regulator; an unlicensed site can display an RTP number with no such oversight. If you set a budget, treat a slot session as money you may lose in full, and use deposit or time limits before you start, not after a feature has failed to appear.

Online slots should be played, if at all, only on sites licensed in a U.S. state that has authorized internet gaming, and only when you are physically in that state. Unlicensed sites can display any RTP number they like without a U.S. regulator testing the game. See the state legality guide and the responsible gambling page.

See also: all game guides, where online casinos are legal, and responsible gambling help.