Roulette is one of the simplest casino games to learn and one of the easiest to understand mathematically. Once you see where the zero fits in, you know exactly what every bet costs.

The Wheel

  • European roulette: 37 pockets, numbers 1 to 36 plus a single 0.
  • American roulette: 38 pockets, numbers 1 to 36 plus 0 and 00.

Numbers alternate between red and black; the zeros are green. At online casinos you will find both, in RNG and live-dealer versions.

Inside Bets

BetCoversPays
Straight1 number35 to 1
Split2 numbers17 to 1
Street3 numbers11 to 1
Corner4 numbers8 to 1
Six line6 numbers5 to 1

Outside Bets

BetCoversPays
Red or black, odd or even, 1-18 or 19-3618 numbers1 to 1
Dozen or column12 numbers2 to 1

Where the House Edge Comes From

The payouts are set as if the zero did not exist. A straight bet pays 35 to 1, which would be fair on a wheel of 36 numbers, but the wheel has 37 (or 38).

  • European: the edge is 1 in 37, about 2.70% on every bet.
  • American: 2 in 38, about 5.26%, almost double.

The edge is the same whether you bet on one number or on red. The bet changes how often you win and how much, not what it costs you on average.

Rules That Help

Some European tables apply la partage or en prison on even-money bets: when the ball lands on zero, you get half your stake back, or the bet stays for the next spin. That halves the edge on those bets to about 1.35%. Look for it in the table rules.

Systems Do Not Change the Edge

Every system, from the Martingale to its alternatives, rearranges bets but cannot change what each one costs. Past spins have no effect on the next one: after ten reds in a row, black is exactly as likely as it always was.

Playing Sensibly

  • Choose European over American whenever you can.
  • Set a session budget and a stop point: see bankroll management.
  • Check how roulette counts towards a bonus before you accept one: it is often weighted at 10% or less, as explained in wagering requirements.