The classic game of roulette is perhaps the most recognizable symbol of casino gambling worldwide. Although the core concept —betting on where the white ball stops— remains identical everywhere, not all roulette wheels offer the exact same odds. The casino world features two main versions that dominate the casino floors: the US version and the European wheel. Knowing the massive variations between the two styles is incredibly important for any player wanting to maximize their chances of winning.
The Green Zeroes: The Double Zero Factor
The most significant difference between the wheels is found directly on the wheel. The classic European layout contains 37 numbers: the standard 1-36, and one single green zero. On the other hand, the US variation features 38 total pockets. It has the same numbers 1 through 36, a single zero, and an additional green pocket: the 00. This one additional space might not look like a big deal to a casual tourist, but mathematically, it ruins the math for the player.
How the Double Zero Ruins Player Profitability
In roulette, the winning odds paid are calculated as if there were only 36 numbers. To illustrate, guessing the exact number returns 35 times your bet, on both the American and European tables. Because the single zero table only has one green slot, the casino's built-in mathematical advantage is a very reasonable 2.70%. However, because the double zero wheel adds that second green slot but pays the same odds, the casino's advantage skyrockets to a terrible 5.26 percent.

Always look for the single zero when gambling online. There is zero benefit to playing the American version. The 'Five Number Bet' only exists on the double zero layout and is the absolute worst bet, with a massive 7.89 percent margin. Specific Euro tables use the En Prison mechanic, which reduces the casino margin on red/black wagers to a tiny 1.35%.

The Ultimate Breakdown: American vs European
To make the difference completely clear, here is this simple chart. It shows the exact reason why pros always hunt for the European layout.

CharacteristicSingle Zero WheelDouble Zero Wheel Spaces on Wheel37 (1-36 plus 0)38 (1-36 plus 0 and 00) Number of Green Zeroes1Double Zero Casino Advantage2.70% (Very Good)High at 5.26% Lowest Possible Edge (with La Partage)1.35% on even money betsFixed at 5.26%

To wrap it up, the American wheel's extra slot is nothing more than a casino trick to drain your bankroll faster from casual tourists. No matter if you are wagering at a lavish casino in Las Vegas or gambling at an online casino from your smartphone, your first goal should be locating a single zero game. Refusing to play the American version is the easiest and most effective way to mathematically improve your long-term returns.