Return to Player Explained for Slots

The definition

Slots are games of chance with a house edge. No strategy, pattern or timing changes the odds in the player’s favor, most players lose money over time, and nobody should gamble money they cannot afford to lose. Anyone struggling with gambling can contact a local support service.

Return to player, usually shortened to RTP, is the percentage of all money wagered on a slot that the game is designed to pay back over the long run. A game with an RTP of 96 percent is designed to return $96 for every $100 wagered, on average, and to keep $4. That $4 is the house edge, so RTP and house edge always add up to 100 percent. The same idea is discussed for all casino games under house edge.

It is a theoretical figure

The RTP is worked out from the game’s design: every possible outcome, how likely it is and what it pays. Averaging all of these gives the percentage. It is calculated mathematically, and it is often described as theoretical because it is a property of the design, not something measured in any one player’s experience.

Because it is an average over an enormous number of spins, it only becomes dependable in practice at very large volumes. This is the law of large numbers at work. An operator across millions of spins will see results that sit close to the figure. A single player’s few hundred spins can land far from it.

A hypothetical example

Take a slot with an RTP of 96 percent and a $1 stake.

• Over 1,000 spins: wagered = $1,000. Expected return = $1,000 x 0.96 = $960. Expected cost = $40.
• Over 100 spins: wagered = $100. Expected return = $96. Expected cost = $4.

Those are averages, not forecasts. In an actual 100-spin session, the result might be a loss of $60, a loss of $4, or a gain, depending on how the random results fall. The 96 percent does not mean the session will finish with $96 of the $100. What it means is that if you could repeat that session a very large number of times, the average return would approach $96.

What RTP says about one session

Very little. Several points are worth keeping in mind.

1. A session is a tiny sample. The spread of results around the average is wide for a short run, especially on games where payouts are uneven. This spread is captured by the standard deviation and by slot volatility. Two games with the same RTP can be very different to play.
2. RTP does not tell you when wins come. A game does not catch up to its return on a schedule. After a long run of losses, the next spin is not more likely to pay. Believing otherwise is the gamblers fallacy.
3. Large wins hide in the average. Part of the RTP often comes from rare, large payouts, such as features or progressive jackpots, which a typical session never reaches. A player who never hits them experiences a return below the average. Some of the figure is “in” events most players will not see in a session. The share carried by features is explained in the article on bonus rounds.
4. It does not reset. A game does not track your own results to bring them toward its RTP.

Reading a published figure

A few cautions apply when you come across an RTP number:

• Some games are offered in more than one configuration, with different RTP settings. The value depends on the version, so the figure for the game you are playing is the one that counts, and the game’s help or rules page is the place to check it.
• A published RTP is a design statement. Independent testing of random number generators and payout settings, described under game certification, is how the claim is checked, and it varies by place.
• A figure that sounds high can still carry a significant expected cost. A difference of 96 percent versus 94 percent might seem small, but the house edge goes from 4 percent to 6 percent, which is half again as much. At $1 per spin and 1,200 spins per hour, those are $48 versus $72 in expected hourly cost.
• RTP does not account for what you do with a bonus. Wagering requirements and game weighting change the effective cost of play when promotions are involved.
• The percentage is measured against the total stake, so it does not reflect how lines or ways affect cost per spin. See pay lines for how the total stake gets built.

What it is good for

RTP is useful for comparing the long-run cost of games on equal terms, because it turns a game into a single number. It is not a promise about any session and not a reason to expect a particular result. A higher RTP means a lower average cost, not that a player is likely to come out ahead. Every slot with an RTP under 100 percent is expected to cost the player money in the long run.

When using the figure in practice, treat it as a way to estimate the expected cost of an evening, include that cost in an entertainment budget, and remember that the real outcome of a session is random. A slot with a lower RTP is not “worse” in a single hour in any predictable way, and one with a higher RTP is not safe.