Roulette is one of the most popular games to be found at both online and bricks and mortar casinos and its enduring appeal is very much down to its simplicity. People just don’t like playing games they don’t understand, and roulette is as simple as they come: you place a bet on the outcome of a ball that is spun around a wheel with numbers. If your number / color / range comes up, you are a winner.
But while the principles of the game are the same across the world, it is important to note that there are rule variations that can make a significant difference to the house edge, and hence your chances of turning a profit. The main variants are United States Roulette and European roulette.
The roulette wheel in the United States version of the game is split into 38 slots: numbers one to 36, a zero and a double zero. The European roulette wheel, in contrast, has only one zero along with the one to 36 numbers, hence 37 slots in total. While this might not seem overly important (what’s one extra zero?), you would be foolhardy not to beware of that extra zero on American versions of this great game.
Let’s do the math. The house edge (or the expected value) can be summed up as the proportion of their bet the player would expect to lose if they were to play for ever. Practically speaking, assuming a player bets on a single number at US roulette, there is a probability of 1/38 that the ball will land on that number. If the player wins they are paid out at 35 times their bet, hence the expected value (and thus the house edge) is calculated as such:
-1×37⁄38 + 35×1⁄38 = -0.0526
This gives a house edge of 5.26% on American roulette. But do the same for the European version, which has just the single zero and you get:
-1×36⁄37 + 35×1⁄37 = -0.0270
Therefore the house edge for European roulette is just 2.7%, just over half that of its US counterpart. Add to that the fact that many European roulette versions give you half your bet back on evens bets (red or black, for instance) if the zero comes up and this really is a no-brainer: always, always choose European roulette over the American version. At least if you want to maximize your chances of winning!