The odds of the roulette wheel depend on what version of the game is being played. Different versions have different setups, and thus have different odds and a different house edge.
House edge is the advantage the casino has over the players and is the percentage of chips that are taken from the winnings of players. For French roulette, the single zero roulette version, the house advantage or edge is 2.7 percent. For American roulette, the double zero version, it is 5.26 percent and is equal 7.9 percent on the 5-number bet (0-00-1-2-3).
A lot of players prefer to play French roulette because it has a lower house edge. French roulette has better odds than American roulette also because it has one zero, which means that for a straight number bet, players have a 1/37 chance of winning. American roulette has 38 number slots, so for a straight number bet the chance is 1/38 instead of 1/37.
This shows the odds are primarily affected by the version of roulette being played but also are affected by the bet itself. As noted earlier, different bets have different odds.
There are certain rules that can affect these odds. These rules are not implemented in every casino. Some of these rules include:
The En Prison Rule (In Prison):
This rule is applied on the bets that pay even money, such as odds/evens, blacks/reds and 1st half/2nd half. If players place any of these bets and the ball lands on the zero, the player will be able to take half of his bet or keep it all for the next spin. If the ball lands on zero again during the next spin, the entire bet will be lost.
The La Partage Rule:
This rule is quite similar to the previous rule but players will lose half the bet. The second option, to keep the bets for a second spin, is not available.
These two rules cut down the edge of the house on even money bets down to half because they give players a second chance.