House edge explained: what casino games cost on average

How the casino’s built-in advantage is defined & calculated, what it looks like game by game, how it relates to RTP & why it only shows over many bets.

What the house edge is

The house edge is the advantage a casino builds into a game. Wizard of Odds defines it as “the ratio of the average loss to the initial bet”, meaning the amount a player loses on average, measured against the stake they started with.

The Gambling Commission says the house edge “gives a measure of the percentage that a casino would expect to keep, on average, from each hand or spin, given normal patterns of play.” It describes roulette, blackjack & punto banco as bankers’ games & games of unequal chance, where the way the game works gives the casino the advantage.

eCOGRA makes the same point about roulette, blackjack & punto banco. The Wikipedia article on casino games adds that the edge is also called the vigorish, & defines it as “the casino profit expressed as a percentage of the player’s original bet.”

Where the edge comes from

According to Wikipedia, the player’s disadvantage exists because the casino does not pay winning bets at the game’s “true odds”, the payout that would be fair given the chance of winning or losing. Its example is a bet on one number of a single die: the true odds would pay 6 times the stake, with the stake returned, but a casino may pay only 4 times.

eCOGRA puts it this way: “the house edge is the difference between the true odds of a game and the odds that a casino offers the player.” It adds that the percentage is determined by the game’s rules.

Wizard of Odds looks at the same gap from the player’s side. In its craps appendix it says the house edge is “just the product of the player’s edge and -1”. The player’s edge is the player’s average result per unit staked, normally a negative number, so reversing its sign gives the house edge.

How to calculate it: a worked example

The method in Wizard of Odds’ craps appendix has two steps. First, the expected return is the sum, over every possible outcome, of that outcome’s probability multiplied by what it returns. Second, “The player’s edge is the expected return divided by the initial bet.”

Wikipedia applies this to American roulette, which has two zeroes (0 & 00) & 36 other numbers, 18 red & 18 black. A 1-unit bet on red wins with a chance of 18/38 & loses 1 unit with a chance of 20/38.

The expected value is (18/38 x 1) + (20/38 x -1) = 18/38 – 20/38 = -2/38, or -5.26%. The house edge on that bet is therefore 5.26%. A European wheel has only one zero, which Wikipedia says gives an edge of 1/37, or 2.7%.

The same sum works for dice. For the craps bet Any 7, Wizard of Odds calculates [(6/36) x 4 + (30/36) x (-1)] / 1 = -6/36, about -16.667%, so the house edge is about 16.67%.

It also works outside the casino. Wizard of Odds gives a sports example where you bet $11 to win $10 with a 50% chance of winning: the expected return is 0.5 x 10 + 0.5 x (-11) = -0.5, & dividing by the $11 stake gives a player’s edge of -1/22, about -4.545%.

Typical house edges by game

Wizard of Odds publishes a table of house edges for popular casino bets. It says the figures “are based on optimal or near-optimal player strategy”.

Card games in its table: blackjack under liberal Vegas rules 0.28%; video poker, full-pay Jacks or Better, 0.46%; baccarat banker bet 1.06%, player bet 1.24% & tie bet 14.36%; Caribbean stud poker 5.22%; three card poker pairplus 7.28%.

Dice & wheel games: craps pass line 1.41%; single-zero roulette 2.70%; double-zero roulette 5.26%. Slot machines run from 2% to 15%, a range Wizard of Odds bases on the returns available from a major manufacturer, & keno from 25% to 29%.

Wikipedia gives a similar spread, with some games having an edge “as low as 0.3%”, keno up to 25% & slot machines up to 15%. It also notes that casinos have traditionally refused to reveal the house edge on their slots.

For skill games such as blackjack, Wikipedia says the edge is “the house advantage from optimal play”, without techniques such as card counting. The set of optimal plays is known as basic strategy, & it depends on the specific rules & the number of decks; even with it, the blackjack figure in Wizard of Odds’ table stays above zero.

House edge vs RTP

Return to player, or RTP, is the percentage of the money staked on a game that it pays back to players over time. eCOGRA says RTP “represents the opposite side of the house edge”: on a game with a 95% RTP, “The remaining 5% represents the house edge or profit for the casino.”

eCOGRA’s European roulette example shows the two figures meeting. A straight-up bet on one number wins with a probability of 1/37 & pays 35 times the stake plus the stake back, so the expected return is 36/37, or 97.30%, which leaves the 2.70% single-zero edge.

RTP is a long-run figure. The Gambling Commission says “The %RTP is an average achieved over a significant number of game plays and not each time the gaming machine is played”, & that on a machine showing 85% RTP “you should not expect to win an average of 85 pence for every £1 you stake during a playing session.”

eCOGRA adds that a player’s personal RTP can be higher or lower over a small number of plays, but “usually converges to the payback ratio over millions of spins”.

What the edge costs per bet & per session

Multiplying the stake by the edge gives the average cost of a bet. Wizard of Odds says a player who knows the blackjack edge is 0.6% can assume that for every $10 original wager “he will lose 6 cents on the average.” eCOGRA gives the same kind of figure for American roulette: at about 5.3%, the casino keeps around £5.30 of every £100 bet on average.

An average says little about one session. Wikipedia works through ten 1-unit spins of American roulette: the average house profit is 10 x 1 x 5.26%, or 0.53 units.

Over the same ten spins the standard deviation, a measure of how widely actual results spread around the average, is 3.16 units. Wikipedia notes the standard deviation “is many times the magnitude of the expected loss”, which is why a short session can end well ahead or well behind.

Why the casino profits over the long run

Wikipedia explains that the expected loss grows in proportion to the number of rounds played, while the standard deviation grows only with the square root of that number. As play continues the expected loss overtakes the swings, & Wikipedia concludes: “This is why it is impossible for a gambler to win in the long term.”

It adds that the high ratio of short-term swings to expected loss is what “fools gamblers into thinking that they can win.”

The law of large numbers describes the same effect. Wikipedia says that while a casino may lose money on a single spin, “its earnings will tend towards a predictable percentage over a large number of spins”, but the law applies only when a large number of observations are considered, & there is no principle “that a streak of one value will immediately be ‘balanced’ by the others”.

The house edge is not the same as hold. Wizard of Odds defines hold as “the ratio of chips the casino keeps to the total chips sold”: a blackjack table that keeps $300 of $1,000 in chips sold has a 30% hold. It notes that hold depends on how long players sit & how money circulates, so it cannot be worked out by mathematics alone.

Financial limits & timeouts

The Gambling Commission has set out changes to its Remote Gambling & Software Technical Standards on financial limits, & its blog says “All these changes are designed to help empower consumers to have greater awareness and control over their gambling.” In a blog post first published on 23 October 2025, the Gambling Commission said that from 31 October 2025 “all gambling businesses must” “prompt new customers to set a financial limit before they make their first deposit and make it easy for them to review and alter their limit”.

The same changes require businesses to “present setting a financial limit as the default choice” & to remind customers every six months to review their account & transaction information.

A second stage requires businesses to offer gross deposit limits, the only type of limit that may be called a “deposit limit”. In an update dated 26 May 2026, the Commission said it had extended the implementation date for these changes from 30 June 2026 to 30 September 2026.

The Commission also describes timeouts: “If you choose to take a timeout, you can block yourself from gambling for up to six weeks.” It says timeouts can help people keep track of their spending & make sure they are not becoming dependent on gambling.

Questions

What does a 5.26% house edge mean?

It means the casino expects to keep, on average, 5.26% of each original stake over many bets. Wikipedia’s example is a 1-unit bet on red in American roulette, where ten spins cost 0.53 units on average.

Is RTP the same as house edge?

They describe the same thing from opposite sides. eCOGRA says a game with a 95% RTP leaves a 5% house edge for the casino.

Which casino bets have the lowest house edge?

In Wizard of Odds’ table, which assumes optimal or near-optimal play, the craps odds bets have the lowest house edge, at 0.00%. Other low figures in the table include blackjack under liberal Vegas rules at 0.28%, Spanish 21 with the dealer standing on soft 17 at 0.40% & full-pay Jacks or Better video poker at 0.46%. At the other end, Sic-Bo runs from 2.78% to 33.33%, the highest figure in the table, & keno runs from 25% to 29%.

Can a player beat the house edge in the short term?

Yes, results can swing either way over a few bets. Wikipedia shows that after ten 1-unit roulette spins the standard deviation of 3.16 units is far larger than the 0.53-unit expected loss, but it says a gambler cannot win in the long term.

Is hold the same as house edge?

No. Wizard of Odds defines hold as the share of chips sold that a table keeps, such as 30% when $300 of $1,000 stays with the casino, & says it depends on how long players sit & how money circulates.

Sources

• wizardofodds.com
• wizardofodds.com
• en.wikipedia.org
• en.wikipedia.org
• ecogra.org
• gamblingcommission.gov.uk
• gamblingcommission.gov.uk
• gamblingcommission.gov.uk

Sources checked 31 October 2026. Information only. 18+.