Roulette Odds Calculator
One Extra Pocket Nearly Doubles the House Edge
A European roulette wheel has 37 pockets (1–36 plus a single zero); an American wheel adds a second zero for 38 pockets. That single extra pocket doesn't change the payout odds on any bet, but it does change the probability of winning — and because payouts stay fixed while win probability drops, the house edge on the American wheel comes out to nearly double the European figure across every standard bet type.
The Formula
P(win) = Numbers Covered / Total Slots
House Edge = −(P(win) × Payout − P(lose) × 1) × 100
House Edge = −(P(win) × Payout − P(lose) × 1) × 100
Standard Bets, Both Wheel Types
| Bet type | Numbers covered | Payout | European (37) edge | American (38) edge |
|---|---|---|---|---|
| Straight up | 1 | 35:1 | 2.70% | 5.26% |
| Split | 2 | 17:1 | 2.70% | 5.26% |
| Street | 3 | 11:1 | 2.70% | 5.26% |
| Corner | 4 | 8:1 | 2.70% | 5.26% |
| Six line | 6 | 5:1 | 2.70% | 5.26% |
| Dozen / Column | 12 | 2:1 | 2.70% | 5.26% |
| Even-money (red/black, odd/even, high/low) | 18 | 1:1 | 2.70% | 5.26% |
The house edge is identical across every standard bet type on a given wheel — it's a property of the extra zero pocket(s), not of how many numbers a specific bet covers.
Where This Gets Used
- Choosing between wheel types — when a casino offers both European and American tables, the European wheel carries roughly half the house edge on identical bets.
- Evaluating a custom or unusual bet — entering nonstandard coverage and payout combinations to check whether they match the standard edge or deviate from it.
- Understanding the "long run" mathematically — house edge describes the average outcome over many spins, not any individual spin's result.
How to Use This Calculator
- Choose Wheel Type — European (37 slots) or American (38 slots).
- Enter Numbers Covered by the bet.
- Enter the Payout, expressed as "to one."
- Select Calculate to see the win probability and house edge.
Related Calculations
Compute the house edge on any other wager with the House Edge Calculator, or check craps point probabilities with the Craps Odds Calculator.