RTP, volatility and house edge explained
Three numbers describe the mathematics of almost every casino game. What each one measures, how they relate, and what they cannot tell you.
Two sides of one number
Return to player, or RTP, is the share of all money wagered on a game that is paid back to players over the long run. A slot with an RTP of 96 percent is designed to return, on average, 96 units for every 100 staked.
House edge is the same figure seen from the operator's side: the share of each wager the game is expected to keep. It is simply 100 percent minus RTP, so a 96 percent RTP means a 4 percent house edge. Table games tend to be described by house edge and slots by RTP, largely by convention.
Some reference points, which follow directly from the rules of the games:
- European roulette has 37 pockets and pays 35 to 1 on a single number, giving a house edge of 2.70 percent.
- American roulette adds a second zero for 38 pockets at the same payout, which raises the edge to 5.26 percent.
- Blackjack played with optimal basic strategy typically has an edge of around 0.5 percent, varying with the table rules. Played without that strategy, the edge is considerably higher.
- Online slots commonly sit between about 94 and 97 percent RTP.
Every commercial casino game has a positive house edge. That is the business model, and no betting pattern or staking system alters it.
What long run means
RTP is a statistical expectation, verified in testing over millions or billions of simulated rounds. It is not a promise about an evening's play. Over a few hundred spins, actual results vary widely around the average, in both directions. A player can finish a short session well ahead on a low-RTP game or lose an entire budget quickly on a high-RTP one.
Two further points are often misunderstood. First, RTP applies to the total amount wagered, not to the amount deposited. A player who recycles winnings stakes far more than the original deposit, and the house edge is applied to every one of those wagers. Second, games that use a certified random number generator have no memory. A slot is never due to pay, and a run of losses does not change the odds of the next spin.
Volatility
Volatility, also called variance, describes how a game's returns are distributed. Two slots can both have a 96 percent RTP and feel entirely different.
- A low-volatility game pays small amounts frequently. Balances tend to drift down gradually.
- A high-volatility game pays rarely, with occasional large wins making up a big part of the overall return. Long losing stretches are a normal part of how such a game behaves.
Studios usually publish volatility as a simple label such as low, medium or high, or on a numbered scale, and there is no single industry standard for the measure. A related figure is hit frequency, the share of spins that return anything at all. It should be read with care, since a return smaller than the stake still counts as a hit.
Where the figures come from
In regulated markets, game mathematics and random number generators are tested by independent laboratories before release, and many regulators require the theoretical RTP to be available to players, usually in the game's help or information screen. Some jurisdictions also require operators to monitor actual returns against the theoretical figure.
One detail matters in practice. Many studios supply the same slot in several RTP configurations, for example 96, 94 and 92 percent, and the operator chooses which to deploy. A figure quoted in a review or on a studio's website may not match the version running at a particular site. The information screen inside the game is the authoritative source.
Progressive jackpot games are a special case. A slice of each stake feeds the jackpot pool, and the published RTP may or may not include that contribution, so the base game can return noticeably less than the headline number.
What the numbers cannot do
RTP, house edge and volatility describe the cost and texture of a game. They do not make a game profitable for players, and they are not tools for choosing a game that will win. Their practical use is in understanding that the expected cost of play is the house edge multiplied by the total amount wagered, and that higher volatility means wider swings around that expectation.
Licensed operators provide deposit limits, session reminders and self-exclusion, and those tools remain the reliable way to keep gambling within a budget set in advance.