Product
House Edge
Definition
The operator's structural mathematical advantage in a casino game, expressed as the percentage of each stake retained over the long run. The complement of return to player.
Key takeaways
- House edge is the percentage of total stakes a game is mathematically designed to retain for the operator over the long run.
- It is the complement of RTP: a 96% RTP game carries a 4% house edge, and the two always sum to 100%.
- House edge is a property of the game’s model, not a prediction of any individual session.
- A low house edge does not mean low risk to the player - stake size and session length matter far more to the amount lost.
Formula
House edge (%) = 100 − RTP Expected operator retention = Total wagered × House edge
For sports betting the equivalent concept is usually called margin or overround on a market, and the realised figure is called hold. They answer the same question - what share of stakes does the book expect to keep - but are calculated from odds rather than from a game model.
Worked example
The figures below are round and illustrative.
A game with a 4% house edge takes 10,000,000 in stakes:
- Expected operator retention = 10,000,000 × 0.04 = 400,000
- Expected return to players = 9,600,000
The word doing the work is expected. Over a single day, or a single player, actual retention can land far above or below 4%. The edge only asserts itself over a very large number of plays.
Why it matters
House edge is the design feature that makes a casino game profitable regardless of individual outcomes. A game with a 96% return to player carries a 4% house edge, meaning that across a very large number of rounds the operator retains 4% of everything staked. The figure is theoretical and describes long-run expectation, not any single session, which is why short-run results diverge wildly from it and why volatility is a separate characteristic entirely.
Edge varies enormously by game and by decision quality. European roulette carries a single-zero edge of about 2.7%, American double-zero roulette roughly 5.26%, while blackjack played with correct basic strategy can fall below 1%. Slots vary by title and sometimes by configured RTP band, which is why several regulators require the figure to be disclosed in game information. For operators the edge combines with game speed to determine revenue per hour, and a fast low-edge game can out-earn a slow high-edge one, a point often missed when games are compared on RTP alone.
House Edge vs RTP (Return to Player)
| House Edge | RTP (Return to Player) |
|---|---|
| Stated from the operator’s side: the share of stakes retained. Lower is better for the player. | Stated from the player’s side: the share of stakes returned. Higher is better for the player. |
They are the same fact from opposite ends and always sum to 100%. Casino games are usually quoted by RTP; table games and sports markets more often by house edge or margin.
The bottom line
House edge is the operator-side statement of a game’s mathematical model. It is reliable for comparing games and unreliable for predicting what any one player will experience.