Roulette odds: why one extra zero nearly doubles the house edge

A sourced look at single- & double-zero wheels, what each bet pays against its true odds, the rules that soften the edge, & why doubling after a loss does not change it.

European vs American wheels

A US roulette wheel has 38 numbered slots: the numbers 1 to 36, a zero & a double zero, according to Wizard of Odds.

What most people call European roulette is played on a 37-number wheel with one zero only. Wizard of Odds says the payouts are the same as in American roulette, & that single-zero roulette is the standard outside the United States, though it can also be found in some US high-limit rooms.

Evolution, which streams live dealer roulette online, draws the same line in its own games. Its French Roulette wheel “features the numbers 1 to 36 and a single zero”, while its Live American Roulette adds “an additional double-zero number (00) on the wheel and table layout”, along with an extra “Five Bet”.

What each bet pays

Roulette payouts are usually quoted “to one”. A win at 35 to 1 pays 35 units of winnings & the original stake is returned as well.

Pennsylvania’s gaming regulations set out an official roulette paytable: a straight bet on one number pays 35 to 1, a split on two numbers 17 to 1, three numbers 11 to 1, four numbers 8 to 1, the first five numbers 6 to 1 & six numbers 5 to 1.

The “outside” bets, which cover larger groups of numbers, pay less. A column or a dozen pays 2 to 1, while red, black, odd, even, 1-18 & 19-36 each pay 1 to 1, which is why they are called even-money bets.

Wizard of Odds warns that some electronic roulette games short-pay, meaning they pay less than these standard figures. On a double-zero wheel, paying 34 to 1 instead of 35 to 1 on a single number raises the house edge, the share of money bet that a player can expect to lose over time, from 5.26% to 7.89%.

Electronic games also often quote wins “for one”, meaning the original stake is not returned on top. Wizard of Odds says that to compare these with standard odds, subtract one: 36 for 1 is the same as 35 to 1.

Payouts vs true odds: a worked example

The house edge comes from the gap between what a bet pays & how often it wins. Take a single-number bet, which pays 35 to 1 on both wheels.

On a European wheel with 37 slots, one number comes up on average once in 37 spins. Bet one unit on it 37 times & you stake 37 units; the single win returns 36 (35 in winnings plus the stake), leaving a loss of 1 unit. One unit lost in 37 is 1/37, or 2.70%.

On a 38-slot American wheel, the same number comes up on average once in 38 spins. Stake 38 units & the one win still returns 36, a loss of 2 units in 38. That is 1/19, or 5.26%.

These match the edges Wizard of Odds gives for each wheel. The payout stays the same while the extra slot adds another losing outcome, which is why the 00 nearly doubles the edge.

The house edge on each wheel

According to Wizard of Odds, every bet on a single-zero wheel carries a house edge of 2.70%. On a double-zero wheel every bet carries 5.26%, except the 0-00-1-2-3 combination (the “first five” bet paying 6 to 1), which carries 7.89%.

Wizard of Odds says triple-zero roulette, played on a 39-number wheel, premiered at the Venetian in Las Vegas in September 2016 & has an edge of 1/13, or 7.69%, on every bet. It adds that it believes the Marina Bay Sands in Singapore became the first casino to offer quadruple-zero roulette in 2024, with an edge of 10% on every bet.

Each extra zero also lowers the chance of winning an even-money bet. According to Casino.org, a bet on red or black wins 48.65% of the time with a single zero, 47.37% with a double & 46.15% with a triple.

La partage & en prison

Some single-zero tables soften the edge on even-money bets. Under la partage (French for “sharing”), a player loses only half an even-money stake when zero lands, according to Wikipedia’s entry on en prison.

Under en prison (“in prison”), the stake is left on the table for the next spin instead. Wikipedia says that if the bet then wins, the stake is returned, & if it loses, it is forfeited; Wizard of Odds adds that a released bet comes back without winnings. Casinos differ on what happens if zero comes up a second time.

Wizard of Odds says the expected value, the average result per bet over time, is the same under French rules whichever option the player takes. Wikipedia puts the house edge with la partage at 1.35%, but only on two-sided outside bets, & Wizard of Odds gives the same 1.35% for single-zero wheels with these rules at several Nevada casinos.

Atlantic City uses its own version on double-zero wheels: if the ball lands in 0 or 00, the player loses only half of an even-money bet. Wizard of Odds says this lowers the edge on those bets to 2.63%.

These rules are the exception in the United States. Wikipedia says most US casinos do not use la partage or en prison, so an even-money stake simply loses when zero comes up. Evolution says its live French Roulette uses la partage.

Why the Martingale doesn’t change the edge

The rules of the Martingale set out by Wizard of Odds say: “The Martingale is generally played on even money bets.” The same rules add: “If the result of your last bet is a loss, then double your next bet size, if you can.” Casino.org says the idea is that the eventual win recovers all previous losses plus a profit equal to the original stake.

Casino.org explains why this fails: “no amount of information about past results can predict future outcomes with accuracy better than chance.” Each spin is independent, & every roulette bet has a negative expected value, so “the house advantage on a standard American or European wheel does not magically disappear because a bet is doubled.”

Wizard of Odds reaches the same conclusion: “not only won’t the Martingale eliminate the house edge, it won’t even dent it.” It says the expected ratio of losses to amount bet will approach the house edge the more someone plays.

Losing streaks, bankrolls & table limits

Wizard of Odds gives an example of a player with a $100 winning goal & a $6,300 bankroll, the total money set aside for play. A run of losses forces bets of $100, $200, $400, $800, $1,600 & $3,200, & the sixth bet must win just to finish $100 up.

Its tables show the trade-off. With 63 units on single-zero even-money bets, enough for six losing bets in a row, the player reaches the 1-unit goal 98.17% of the time, but averages only about 53.5 one-unit wins between each 63-unit loss.

Long losing runs are more common than they feel. Casino.org says six losses in a row has a 1.8% probability on a single-zero wheel, but the chance of that streak happening at some point in 200 plays is about 84%.

A 10-loss streak carries about an 11% chance in 200 plays, Casino.org says, at which point a player would “need to pony up $10,240 just to try to recoup a single $10 bill”. It adds that 17 doublings of a $10 base bet push a single wager to $1,310,720.

Table maximums stop the doubling well before that. Casino.org says limits vary by pit, game & time of day but are commonly $1,000 to $2,500 on outside bets at standard Strip tables & $5,000 to $10,000 in high-limit rooms.

Chasing losses & getting help

One of the questions the NHS asks people unsure whether gambling is causing them problems is: “Have you tried to win back money you have lost (chasing losses)?” The Martingale is built around winning back earlier losses with the next, larger bet.

The NHS suggests signing up for GamStop, which stops someone using gambling websites & apps for 6 months, 1 year or 5 years. It lists the National Gambling Helpline, run by GamCare, which is free on 0808 8020 133, 24 hours a day, 7 days a week, & advises: “do not view gambling as a way to make money”.

Self-exclusion is a formal agreement not to gamble. The Gambling Commission, in guidance last updated on 27 March 2026, says GAMSTOP ONLINE allows self-exclusion from online operators with one request, & that once an agreement is made the gambling business must close the account & return any money in it.

Questions

What is the house edge in European & American roulette?

According to Wizard of Odds, every bet on a single-zero European wheel carries 2.70%. On a double-zero American wheel the edge is 5.26%, except the 0-00-1-2-3 bet at 7.89%.

Do European & American roulette pay the same?

Yes. Wizard of Odds says the payouts are the same on both, so the extra 00 slot is what raises the edge.

What does la partage do to the odds?

Under la partage an even-money bet loses only half its stake when zero lands. Wikipedia puts the house edge at 1.35% on two-sided outside bets, & says most US casinos do not use the rule.

Does the Martingale system work?

It does not remove the house edge. Wizard of Odds says it “won’t even dent it”, & Casino.org notes that long losing streaks & table maximums can stop the doubling.

Where can someone get help with gambling?

The NHS lists the National Gambling Helpline, free on 0808 8020 133 at any hour, & GamStop, which blocks gambling websites & apps for 6 months, 1 year or 5 years.

Sources

• wizardofodds.com
• law.cornell.edu
• en.wikipedia.org
• games.evolution.com
• casino.org
• wizardofodds.com
• nhs.uk
• gamblingcommission.gov.uk

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