House Edge
The house edge is the percentage of each bet a casino keeps on average over the long run. It ranges from about 0.5% on blackjack played with basic strategy to over 20% on games like keno — and it is the single most useful number for comparing casino games.
| Definition | Casino's average long-run margin per bet |
|---|---|
| Lowest | Blackjack ~0.5%, baccarat banker ~1.06% |
| Highest | Keno and many side bets (10%-25%+) |
| European Roulette | 2.70% |
| American Roulette | 5.26% |
| Applies To | Amount wagered (turnover), not the deposit |
| Inverse Of | Return to player (RTP) |
What the house edge is
The house edge is built into every casino game by setting payouts slightly below the true odds of the outcome. If a bet has a true probability that should pay 36-to-1 but the casino pays 35-to-1, the difference is the edge.
Over a single session results swing wildly, but over thousands of bets the casino’s actual win closes in on the theoretical edge – which is why it is a long-run average, not a prediction for your night.
Why it is the number that matters
Because the edge applies to every wager, it effectively sets the ‘price’ of playing a game. A 1% edge means that, on average, you lose about £1 of every £100 wagered (not deposited); a 10% edge means £10.
Lower-edge games like blackjack and baccarat give far more playing time per pound than high-edge games like keno. Comparing games by house edge – or its mirror, RTP – is the most useful habit a player can build.
A worked example
Suppose you bet £2 per spin on European roulette and play 50 spins in an hour. Your turnover is £100, and at a 2.70% edge your expected loss is about £2.70 for the hour.
Move to American roulette, with its second green pocket, and the edge jumps to 5.26% – the same £100 of turnover now carries an expected loss of about £5.26, almost double, for an identical-looking game. This is why the single most valuable habit is checking the edge before you play, not after.
House edge across common games
Approximate edges under common rules: blackjack with basic strategy around 0.5%; baccarat’s banker bet about 1.06% and player about 1.24%; the craps pass line 1.41%; European (single-zero) roulette 2.70%; American (double-zero) roulette 5.26%; most slots between roughly 2% and 10%; and keno often 20-30%.
Side bets are usually far worse than the main game they sit beside, so a low-edge game can still hide high-edge wagers on the same table.
Theoretical edge versus the casino's actual hold
The house edge is a theoretical figure per bet. A casino’s ‘hold’ – the share of the money players bring that it actually keeps – is usually higher, because players re-bet their winnings and so wager their bankroll many times over.
The edge describes the cost of each bet; the hold describes what happens to a typical bankroll across a whole visit. Both follow from the same maths, but they answer slightly different questions.
Frequently asked questions
Is the house edge per bet or per deposit?
It applies to the amount wagered, not deposited. Because you re-bet winnings, total turnover is usually far higher than your deposit, so the edge applies many times over a session.
Which games have the lowest house edge?
Blackjack with basic strategy (~0.5%), baccarat's banker bet (~1.06%) and the craps pass line with odds are among the lowest.
How is the house edge calculated?
It is the difference between the true odds of an outcome and the payout the casino offers, weighted across every possible result. The shortfall, expressed as a percentage of the stake, is the edge.
Does a 2% edge mean I will lose exactly 2%?
No. It is a long-run average. Any single session can land well above or below it – that short-term spread is volatility – but across enough bets your results trend towards the edge.
Can the house edge ever favour the player?
Only in unusual cases such as certain promotions, advantage-play situations or rare full-pay video poker. By design, ordinary casino bets always carry an edge for the house.
Sources
- Probability theory
- Standard house-edge tables
- Published game rules and payout schedules