Roulette Odds & Probability

The odds on roulette depends on the variant you play and the rules used in that game variation. Anytime players navigate to an online casino, they are offered a dozen or more gaming options. Knowing the probabilities of each version is critical. If you are a high volume player or if you gamble for high stakes, understanding probability will save you hundreds, if not thousands, of dollars a year.

That won’t always be the case. Some of the time, the odds won’t be significantly affected playing one game or another. Many of the European wagers provide new ways to make bets with the same house edge. Below is a complete guide to roulette probability, complete with tips, strategy advice, and the debunking of a few myths.

European Roulette Odds

The most common form of the game online is called “European roulette”. This game offers a 2.70% house edge or 97.3% payout percentage. Every time you wager $10, you can expect to win back $9.73. Gamblers who make $10 bets can expect to lose 27 cents with each spin. This won’t always be the case, of course. It’s an average for every player who plays that form of the game.

To spot a European wheel, you’ll note that it has 37 pockets or slots. These are numbered 0, 1, 2, and so on all the way to the number 36. Half of the pockets are red and half are black, except for one green pocket. When you want to know what game is being played, look for the green pockets. If it only has one (numbered “0”), then it’s a European wheel.

American Roulette Odds

The game played in North America is called “American roulette”. This game offers a 5.26% house edge–almost twice as much as the Euro game. The payout percentage is thus 94.74%, which isn’t particularly good for a casino game. For every $10 you wager, you can expect to lose a little over 53 cents. The reason these bad odds exist is the inclusion of a second green pocket: the “00”. Wheels with this included are called American or Las Vegas wheels. Double-zero roulette is best avoided.

French Roulette – Called Bets

Players often will find a game with the designation “French”. This can be confusing, because the European version of the game is also French, because it first became famous in the small French principality of Monaco, in its famous Monte Carlo casinos. In online gaming, French roulette refers to the game with the called or announced bets. Wagers like orphelins, jue zero, le tiers du cylindre, and voisins du zero are characteristic of this game. In truth, the house edge for this game is also 2.70%. These are interesting new ways of making same-chance bets, often used by high rollers and players in Europe. Learn these wagers and play them, but don’t worry about them positively or negatively affecting your chances.

La Partage Betting

Certain rules affect the basic games described above. One of these is called “la partage”, which literally means “of the parts”. The la partage rule is a good thing for players, so it pays to learn how it works. This rule effects even-money wagers. Those are the 1-to-1 payouts on bets like even/odd, black/red, or high/low. Anytime you make this wager under la partage rules, if the ball lands on a zero slot, you only lose half your bet. This would affect both the single-zero or double-zero versions of the game, though you’ll find these rules applied much more often in the European style of play.

La partage halves the house edge on games it is used. If you play on a European wheel, the house edge drops to 1.35%. At these odds, roulette offers a game comparable to baccarat or craps among the games which require no in-game strategy. When playing on an American wheel, the odds drop from 5.26% to 2.63%, making it a game a player might want to play. If you went to an online casino with the American game with la partage rules (2.63% house edge) and the European game without la partage rules (2.7% house edge), you would want to play the double-zero game. That’s not likely to happen. In live settings, only Atlantic City and a few high dollar sections of Las Vegas Strip casinos offer la partage rules.

I want to point out one more thing about this rule. It only applies to even-money wagers. To get the halved house edge, you’ll need to bet on the even/odd, red/black, or hi/lo. Don’t make inside bets or 2:1 bets, because you’ll be playing by the same old rules.

En Prison Rules

A similar rule is “en prison”, which translates to “imprisonment”. Instead of taking half your bet, this wager puts your bet in prison for a hand anytime the ball lands on a zero. Another spin is made and the winner of that spin gets your original wager. This has the same effect as la partage, though it’s a bit more complicated. If you are offered this option, remember to make only 1:1 bets.

The Progressive Betting Myth

When new players start reading about probability, they are likely to encounter writers who propose using progressive or regressive bets to increase their probability of winning. Some of these methods have the sheen of mathematics, so at first glance, they might appear to be mathematical ways of beating the odds. I can assure you they don’t. The most famous and enduring of these is the Martingale betting technique. This requires you to start each new betting sequence with the same size bet (let say $10). After each win, you go back to the beginning of the cycle and wager $10 on the next spin. After each lose, you double the bet. This would mean a $20 bet after one loss, then a $40 wager, then an $80 wager, and so on.

I hope you see already how this can be a bad thing. With the exponential increase, wager sizes become massive quickly. As long as you win at the end of this sequence, you’ll come out $10 ahead. The problem comes when you have a streak of 5 to 10 losses in a row. You might exceed the bet limit. Also, you’ll be wagering hundreds of dollars in hopes of getting back to that $10 advantage. It becomes a bad proposition.

Plenty of people fall for it, because they believe the classic gambler’s fallacy (the more you lose, the more like it is you’ll win on the next spin). The law of averages doesn’t work that way (or at all), so the odds of winning a $10 bet is the same as the odds of winning a $640 bet when you’ve lost the previous 6 spins. Your odds of winning an even-money bet always sit at just under 50%, due to the presence of the zero slot, which provides a house edge.