The short answer
A European wheel has 37 pockets (0 to 36). An American wheel has 38: the same plus a double zero (00). The payouts are identical, so the extra pocket simply gives the house more winning numbers. The house edge goes from 2.70% to 5.26%, about 1.95 times as much. If you can choose, choose European.
Side by side
| European | American | |
|---|---|---|
| Pockets | 37 (0, 1-36) | 38 (0, 00, 1-36) |
| House edge | 2.70% | 5.26% |
| Chance of one number | 1 in 37 | 1 in 38 |
| Straight-up payout | 35 to 1 | 35 to 1 |
| Special bet | First four (0-1-2-3), 8 to 1 | Top line (0-00-1-2-3), 6 to 1, edge 7.89% |
| Expected loss, $10 × 200 spins | $54 | $105 |
| Wheel starts | 0, 32, 15, 19, 4, 21, 2, 25 ... | 0, 28, 9, 26, 30, 11, 7, 20 ... |
Why the double zero matters
Every roulette payout is based on 36 numbers. On a European wheel there are 37 possible results, so the house keeps 1 in 37 of everything bet over time. On an American wheel there are 38 results, so it keeps 2 in 38. Nothing else changes: red still pays even money, a dozen still pays 2 to 1. The only difference is how often the green pockets swallow the outside bets.
Different number order
The numbers are arranged differently around the two wheels. On the European wheel, numbers alternate red and black and are spread out so neighbours are rarely close in value. On the American wheel, every odd number sits directly opposite the even number after it (1 across from 2, 3 across from 4, and so on), and 0 and 00 are opposite each other too. The order doesn't change any odds, but you'll see it when you watch the ball in our game.
What about French roulette?
French roulette uses the same single-zero wheel as European roulette, often with a French-language table and two extra rules some casinos offer for even-money bets when zero comes up: la partage gives back half the bet, and en prison holds the bet for one more spin. Either rule lowers the edge on those bets. Our game plays standard European and American rules.
Try both
Open the game, press the wrench and switch the wheel between European and American. Your chips are returned when you switch, because some bets only exist on one of the wheels. Play a few hundred spins of each with play money and you'll feel the difference the second zero makes.