Roulette Simulator

Odds and expected value

A European wheel has 37 pockets (0–36); an American wheel adds 00 for 38. Payouts are set as if the zeros didn’t exist, and that gap is the casino’s house edge: 2.70% on European and 5.26% on American wheels.

• Straight number: pays 35:1, wins 1 in 37 (≈ 2.7%)
• Dozen or column: pays 2:1, wins 12 in 37 (≈ 32.4%)
• Red/black, odd/even, high/low: pays 1:1, wins 18 in 37 (≈ 48.6%)

Every bet has the same long-run expectation: wagering 1,000 on a European wheel loses about 27 on average. The one exception is the American 0-00-1-2-3 “top line” (6:1), whose edge is a worse 7.89%.

Why betting systems don’t beat the edge

A strategy only changes when and how much you bet, never the odds of each spin. Try it in the strategy simulator above.

• Martingale (double after a loss): wins small amounts often, but with a base bet of 10 and a table limit of 1,000, seven losses in a row cost 1,270 and the next bet (1,280) exceeds the limit. Seven straight losses on red happen only about 0.94% of the time — yet over hundreds of spins you are likely to hit one.
• Paroli (double after a win): caps losses but needs winning streaks, so most sessions lose a little.
• Fibonacci and D’Alembert: raise bets more gently than Martingale, but long losing runs still add up.

As you add sessions, the simulator’s “loss per amount wagered” converges on the theoretical house edge — the law of large numbers at work.