European roulette: a single zero
37 pockets, probabilities and the difference between odds and payouts.
The wheel layout
A European wheel has 37 pockets: numbers 1 to 36 and zero. There are 18 red numbers, 18 black numbers and one green zero. Zero is not red, black, even or odd for standard outside bets.
A probability example
A red bet covers 18 of the 37 pockets: about 48.65%. A straight-up number covers one: about 2.70%. These chances do not change because one colour appeared repeatedly before.
House edge
With classic payouts and no special rules, the house edge is 1/37, about 2.70%. This is a long-run mathematical expectation, not a predicted loss for every session.
Probabilities calculated from 37 or 38 equally likely outcomes, depending on the variant. Check the table rules.
18+. Winnings are not guaranteed. Read the rules of the version available in your account.