The classic game of roulette is the most famous image of casino gambling worldwide. While the fundamental idea —guessing where a small ball will land— is the same across the globe, not every roulette game are created equal. The casino world features two main versions that dominate the casino floors: American Roulette and European Roulette. Understanding the critical differences between the two styles is incredibly important if you want to play smart.
The Number of Pockets: The One Massive Difference
The primary physical distinction between the wheels is the number of green pockets. The classic European layout contains 37 numbers: the numbers 1 through 36, plus a single green zero (0). Conversely, the American Roulette wheel has thirty-eight slots. It features the same numbers 1 through 36, the single green zero (0), plus a devastating extra pocket: the double zero (00). This one additional space might seem insignificant to a beginner, but in reality, it ruins the math for the player.
The Devastating Impact Ruins Player Profitability
In roulette, the winning odds paid are strictly designed as if the zero did not exist. For example, hitting a single number returns 35 times your bet, no matter the wheel type. Since the Euro version only has one extra pocket (the zero) that causes outside bets to lose, the casino's built-in mathematical advantage sits at exactly 2.7%. But, since the US version has 38 total spaces but pays the same odds, the casino's advantage skyrockets to exactly 5.26%.

Never play the American wheel if both are available. It makes no sense to playing the American version. The Top Line bet only exists on the double zero layout and is the absolute worst bet, with a massive 7.89 percent margin. French roulette games offer the 'En Prison' or 'La Partage' rules, which reduces the casino margin on red/black wagers down to an incredible 1.35%.

The Ultimate Breakdown: The Tale of the Tape
For a fast visual reference, here is this simple chart. It breaks down exactly why smart gamblers always hunt for the single zero wheel.

CharacteristicEuropean RouletteAmerican Roulette Spaces on Wheel37Thirty-Eight Number of Green ZeroesOne (0)Two (0 and 00) Casino Advantage2.7%High at 5.26% Lowest Possible Edge (with La Partage)1.35%Always 5.26%

To wrap it up, the American wheel's extra slot is nothing more than a casino trick to double their profits from uninformed players. Whether you are placing bets at a lavish casino in Las Vegas or gambling at an online casino from your smartphone, your first goal must always be locating a single zero game. Boycotting the double zero is the smartest strategy to mathematically improve your chances of walking away a winner.