The Basic Relationship
Casino games are games of chance with a built-in house edge. No strategy or system changes the odds in the player’s favor over time, and most players lose money over time. Never gamble money you cannot afford to lose.
Two figures are used to describe that built-in advantage. The house edge is the average share of each wager the game is expected to keep. Return to player, usually shortened to RTP, is the average share of each wager the game is expected to pay back. Because every unit wagered is either kept or returned, the two add up to 100%:
house edge + RTP = 100%
So a game with a 4% house edge has an RTP of 96%, and a game with an RTP of 94% has a house edge of 6%.
Checking It With Roulette
On a single-zero wheel, a 1-unit straight-up bet wins with probability 1/37 and pays 35 units of profit, which means 36 units come back in total (35 profit plus the returned stake).
Expected amount returned per unit wagered = (1/37) × 36 = 36/37, about 0.973, or 97.3%.
The house edge is then 1 − 36/37 = 1/37, about 2.70%. And 97.30% + 2.70% = 100%.
On a double-zero wheel, the return is 36/38, about 94.74%. The edge is 2/38, about 5.26%. And 94.74% + 5.26% = 100%.
The two numbers describe the same fact from opposite directions. Neither contains information the other lacks.
Why Both Figures Are Used
Different parts of the industry prefer different phrasing.
- Table games are usually described by the house edge, a cost-oriented figure.
- Slot machines and similar games are usually described by RTP, which is a return-oriented figure. The topic of what return to player means and what it does not covers the details for machines.
The choice is mostly a matter of convention. A reader who learns to flip between them can compare any two games, whichever way the figures are quoted.
An Important Qualification: “Returned” Is an Average
RTP of 96% does not mean that each player gets 96 back out of every 100. It means that, across a very large number of plays, the total paid out is expected to approach 96% of the total wagered. Any individual result can be far higher or far lower. A player can lose everything on a high-RTP game, and another can multiply their stake on a low-RTP game.
For machines, the RTP is a property of the game’s design, set by the game math model. It is a theoretical long-run figure, not a promise about a day, a week or a particular machine. In games that use virtual reels, the probabilities behind each symbol are weighted so that the overall figure matches the target, regardless of how the reels appear.
Per Bet or Per Round?
A subtle trap is the unit of measure. The edge and RTP both need a base: a percentage of what?
- In roulette, the base is clear: the amount of the bet.
- In blackjack, the edge is often quoted per initial wager, but doubling and splitting add money to the round, so the amount actually risked in a round can be larger than the first bet.
- In video poker, RTP is usually quoted for a particular pay table and assumes the player makes the best possible choices. A player who plays less accurately gets a lower figure than the quoted one.
Likewise, a blackjack edge assumes correct basic strategy and depends on the rules. The figure is not one number for the game as a whole but a number for a specific set of rules and a specific style of play.
Does a Higher RTP Mean a Good Bet?
A higher RTP means a lower expected cost per unit wagered, which is a real difference. A 98% game costs, on average, 2 units per 100 wagered, while a 94% game costs 6. But neither number turns the game into a gain. At an RTP below 100%, the average result is still a loss.
RTP also says nothing about how bumpy the ride is. Two games with the same RTP can differ widely in how often they pay and how large the payments are. The hit frequency and the volatility describe that, and the RTP does not.
Quick Conversions
| House edge | RTP |
|---|---|
| 1% | 99% |
| 2.5% | 97.5% |
| 5% | 95% |
| 10% | 90% |
To convert in either direction, subtract from 100. If a figure is quoted as a fraction or a decimal, convert it to a percentage first.
The Practical Takeaway
When a game quotes only one of the two figures, the other is easy to find. Using whichever is more convenient, multiply it by the total amount wagered to estimate the expected cost: the edge times the total wagered is the expected amount kept. The result is an average over many bets, with real outcomes scattered around it, and with the average pointing toward a loss for the player.