How this roulette probability calculator works
This tool estimates your chance of winning roulette bets over multiple spins. Instead of showing only a single-spin percentage, it also calculates what most players actually care about: your probability of hitting a minimum number of wins over a session.
You choose the wheel type, bet type, number of spins, and target wins. The calculator then applies binomial probability to produce session-level outcomes, plus expected value based on your bet amount.
Core roulette probabilities: European vs. American
European roulette (single zero)
European roulette has 37 pockets (0 to 36). That gives slightly better odds for the player than American roulette. For example, a straight-up bet wins with probability 1/37 (about 2.70% per spin).
American roulette (double zero)
American roulette has 38 pockets (0, 00, and 1 to 36). The extra 00 increases the house edge. A straight-up bet wins with probability 1/38 (about 2.63% per spin), and even-money bets drop from 18/37 to 18/38.
Bet types included in this calculator
- Straight Up: 1 winning number, payout 35:1
- Split: 2 winning numbers, payout 17:1
- Street: 3 winning numbers, payout 11:1
- Corner: 4 winning numbers, payout 8:1
- Six Line: 6 winning numbers, payout 5:1
- Dozen / Column: 12 winning numbers, payout 2:1
- Even-Money bets: 18 winning numbers, payout 1:1
For standard bets, roulette payouts are structured so the house edge remains constant for a given wheel. That means changing bet types often changes volatility more than long-term expected return.
What the results mean
Single-spin win probability
This is your chance of winning one individual spin. It comes directly from:
p = (number of winning pockets) / (total pockets)
Probability of at least N wins in S spins
Roulette spins are independent events. Over multiple spins, the number of wins follows a binomial distribution. This gives a more realistic picture of what can happen in a real session than only looking at one spin.
Expected value and expected net result
Expected value estimates your average long-run gain or loss per spin. In roulette, this is negative due to the house edge. The calculator multiplies that expected value by your number of spins and stake to estimate average session outcome.
Example interpretation
Suppose you choose an even-money bet on European roulette, 50 spins, and $10 per spin. Your single-spin win chance is 18/37 (about 48.65%), but your expected return is still negative because losses include the zero outcomes that do not pay. Over many repeated sessions, average results trend toward the house edge, even if short-term streaks can be positive.
Common roulette myths (and the math reality)
- "Red is due after five blacks" — false. Past spins do not change future probabilities.
- "I can recover by doubling forever" — table limits and bankroll constraints make this impossible in practice.
- "Hot numbers stay hot" — roulette outcomes are independent on a fair wheel.
Responsible use
Use this calculator to understand risk, not to chase guaranteed profit systems. Probability tools are most useful when they help you set limits and evaluate decisions with clear expectations. If gambling stops being entertainment, step away and seek support.