Calculate roulette payouts, house edge, win probabilities, and expected value for every bet type. Simulate spins and compare American vs European wheels.
Every roulette bet has an exact mathematical payout, win probability, and house edge — and this calculator lays it all bare. Select American (38 slots with 0 and 00) or European (37 slots with single 0), choose your bet type, and instantly see your real chances and expected return.
The tool covers all standard roulette bets from straight-up (35:1 payout, 2.63% win probability on American) to even-money bets like Red/Black (1:1 payout, 47.37%). A built-in simulation runs hundreds of spins to show how the house edge grinds down bankrolls over time, with a visual bankroll tracker.
The comprehensive bet comparison table is the centerpiece — every bet type side by side with coverage, payout, win percentage, expected value, and house edge. It proves the mathematical truth: on an American wheel, every bet except the Top Line carries an identical 5.26% house edge. Check the example with realistic values before reporting.
Understanding roulette math protects your bankroll. When you see that $10/spin on American roulette costs $52.60 per 100 spins in expected losses, you can make informed decisions about entertainment budgets. The bet comparison table is the clearest demonstration that changing bet types doesn't change the house edge.
This tool is also widely used in probability education. Roulette is one of the simplest games to analyze mathematically, making it ideal for teaching expected value, house edge, and the gambler's fallacy.
Win probability = slots covered / total slots. EV = (win prob × payout × bet) − (loss prob × bet). House edge (American) = 2/38 = 5.26%. House edge (European) = 1/37 = 2.70%. Top Line edge = 3/38 = 7.89%.
Result: Win prob: 47.37%, Payout: 1:1, EV: −$0.53/spin, House edge: 5.26%. Over 100 spins: expected loss ~$52.60.
Betting $10 on Red covers 18 of 38 slots. Each spin has a 47.37% win probability (not 50% due to 0 and 00). The 5.26% house edge means you lose ~$0.53 per $10 bet on average.
American roulette has 38 slots: 1-36, 0, and 00. A straight-up bet pays 35:1, but true odds are 37:1. That gap — paying less than true odds — is where the casino makes money. For every $38 wagered across all numbers, $36 is returned (to the winner) and $2 is kept. That's 2/38 = 5.26%.
European roulette has 37 slots (no 00), so the gap is 1/37 = 2.70%. The smaller gap makes a massive difference over hundreds of spins.
The most dangerous misconception: "Red hasn't come up in 8 spins, so it's due." Each spin is independent. The wheel has no memory. After 8 straight blacks, the probability of red on spin 9 is still 18/38 (47.37%). This is the gambler's fallacy, and casinos profit enormously from it — electronic displays showing recent results exist specifically to encourage this false reasoning.
If you bet $10/spin with a $1,000 bankroll on American roulette, your expected bankroll after N spins is $1,000 − (0.0526 × $10 × N). After 100 spins: ~$947. After 500 spins: ~$737. After 1900 spins: $0 (expected). Variance means some sessions will be better, some worse, but the long-run trajectory always points down.
European has 37 slots (one zero) vs American's 38 (zero + double zero). This halves the house edge: 2.70% vs 5.26%. Over time, you lose money roughly twice as fast on American wheels.
On American wheels, every bet has a 5.26% edge EXCEPT the Top Line (0-00-1-2-3) which has 7.89%. On European wheels, all bets have 2.70%. Bet type doesn't matter — they're all equally bad.
No. Every spin is independent with a fixed house edge. The Martingale (double after loss) doesn't change EV — it just trades many small wins for rare catastrophic losses. No betting system can overcome the mathematical edge.
Martingale requires doubling bets after losses. Starting at $10: after 7 losses you'd bet $1,280. Table limits prevent this, and the expected value remains negative regardless. Labouchere, D'Alembert, and Fibonacci share the same fundamental flaw.
Exactly house_edge × total_wagered. On an American table with $10 average bets and 50 spins/hour across 6 players: 0.0526 × $10 × 50 × 6 = $157.80/hour for the casino.
No. Simulation shows probable outcomes and demonstrates the house edge over time, but each real spin is independent. The simulation is educational, not predictive.