Roulette Odds Calculator
Compare European and American roulette risk before betting
Roulette offers a clear way to see how coverage and payout create very different betting experiences. A straight-up wager on one number can produce a large payout, while a red/black wager wins much more often. Neither profile removes the casino advantage. This roulette odds calculator makes that tradeoff explicit by showing the selected bet’s one-spin win chance, loss chance, payout ratio, expected net return per unit, and house edge.
Roulette wheel choice is the first factor behind the result. A European wheel has 37 pockets: numbers 1 through 36 and one zero. An American wheel has 38 pockets because it includes both zero and double zero. Standard payouts do not increase for that extra pocket, so the American wheel lowers the player’s probability and raises the house edge.
Roulette bet coverage is the second factor. A wager can cover one number, a small group of numbers, a dozen, or 18 numbers on an even-money bet. More covered pockets increase the chance of a hit but reduce the net payout; fewer covered pockets do the reverse. The calculator lets you inspect those distinct probability profiles without treating a frequent win as automatically better value.
Roulette wheel and bet inputs explained
Wheel type sets the number of possible roulette outcomes. Select European for 37 pockets or American for 38 pockets. Because the denominator changes for every supported wager, this selection immediately changes the win probability and the resulting house edge.
Bet type supplies the coverage and standard net payout used in the roulette calculation. A straight covers 1 number and pays 35:1; a split covers 2 and pays 17:1; a street covers 3 and pays 11:1; a corner covers 4 and pays 8:1; and a six line covers 6 and pays 5:1. Dozens and columns cover 12 numbers at 2:1, while red/black, even/odd, and high/low cover 18 numbers at 1:1.
Roulette odds need both coverage and payout to be meaningful. A bet with a higher hit rate generally pays less when it wins, and a bet with a large listed payout generally misses more often. The result panel combines the selected wheel size, covered pockets, and payout instead of showing only one side of that relationship.
Standard roulette bets by coverage and wheel
This roulette comparison table lists the standard wagers supported by the calculator. The American-wheel probabilities are lower in every row because the double-zero pocket adds an additional losing outcome while the posted net payout remains unchanged.
| Bet type | Pockets covered | Payout | European win % | American win % |
|---|---|---|---|---|
| Straight | 1 | 35:1 | 2.70% | 2.63% |
| Split | 2 | 17:1 | 5.41% | 5.26% |
| Street | 3 | 11:1 | 8.11% | 7.89% |
| Corner | 4 | 8:1 | 10.81% | 10.53% |
| Six line | 6 | 5:1 | 16.22% | 15.79% |
| Dozen / Column | 12 | 2:1 | 32.43% | 31.58% |
| Red/Black, Even/Odd, High/Low | 18 | 1:1 | 48.65% | 47.37% |
Although the hit rates differ sharply, the standard roulette bets in this table have the same long-run house edge on a given wheel: 2.70% on the European wheel and 5.26% on the American wheel. Coverage changes volatility and win frequency, not the built-in price of these standard wagers.
How roulette coverage produces probability, EV, and house edge
This roulette calculator assumes every pocket is equally likely. It divides the number of pockets covered by the selected bet by the number of pockets on the selected wheel to find the win probability. The loss probability is the remaining chance. Expected return weighs the net profit on a win against the loss of the stake on a miss.
For standard roulette payouts, the resulting expected value is negative because the listed winnings fall slightly short of fair odds. That shortfall is the house edge: about 2.70% for a standard bet on a European wheel and about 5.26% for the corresponding standard bet on an American wheel. The calculation does not combine unrelated inputs or apply a generic weighted-score model.
Hand-checkable roulette expected-value examples
A European red/black wager is an even-money roulette bet covering 18 of 37 pockets. Its win probability is 18/37, approximately 48.65%, and its loss probability is 19/37, approximately 51.35%, because zero is neither red nor black. With a 1:1 net payout, its expected return per unit is:
EV = (18/37 × 1) - (19/37) = -1/37 ≈ -0.0270
In practical terms, repeatedly staking 1 unit on that European even-money wager has an average net loss of about 0.027 units per wager. That is the calculator’s 2.70% house edge, not a promise about the outcome of any individual spin.
An American straight wager shows the other end of the roulette volatility range. It covers 1 of 38 pockets, so its win probability is 1/38, about 2.63%, and its loss probability is 37/38, about 97.37%. The standard net payout is 35:1:
EV = (1/38 × 35) - (37/38) = -2/38 ≈ -0.0526
The American straight bet therefore has a 5.26% house edge. Its rare, high-profit wins may feel very different from an even-money bet, but the extra double-zero pocket makes its long-run price worse than a comparable standard bet on a European wheel.
These roulette examples explain why bets on one wheel can feel so different yet share a house edge. Payout size and hit frequency change together. They affect the pattern of wins and losses, but standard payouts preserve the same negative expected return for the selected wheel.
Reading the roulette result panel
The roulette result panel answers five related questions. Win probability is the chance that the selected wager hits on one spin. Loss probability is its complement. Payout ratio is the standard net payout. Expected return per unit is the long-run average net result of repeatedly staking one unit. House edge expresses the negative expected return as the casino’s positive percentage advantage.
When comparing roulette bets, do not use just the win percentage or just the payout. Red/black hits more often than a straight bet but pays 1:1; a straight bet pays 35:1 but covers only one pocket. Viewing probability, payout, and expected return together makes the difference between a high-frequency bet and a high-volatility bet clear.
The calculator deliberately does not model roulette betting systems, bankroll limits, table limits, or streaks. It treats spins as independent and pockets as equally likely. It also excludes special rules such as la partage and en prison, which can reduce the edge for certain European even-money wagers. For ordinary published payouts on standard wheels, it reports the central one-spin arithmetic.
Roulette assumptions and limits to keep in mind
This roulette tool uses the standard published payout table and assumes a fair wheel with equally likely pockets. That makes it useful for comparing European and American wheels and for understanding the relationship between coverage, payout, and expected value. Independence is essential: previous spins do not alter the probability of red, black, or any number on the next spin.
The roulette expected return per unit is a net long-run measure. A negative result does not say the next wager must lose, nor does a short winning run refute the displayed house edge. Repetition causes average results to tend toward the calculated value, while individual sessions can vary substantially.
Finally, the payout ratios on this page are net roulette winnings. A 35:1 straight bet returns 35 units of profit for a 1-unit stake; it is not a statement that the total returned amount is 35 units. Using the net payout is why the expected-value formula subtracts the full lost stake when the wager misses.
Roulette odds questions about wheel choice and expected return
Why do standard roulette bets on one wheel share a house edge?
Standard roulette payouts rise as coverage shrinks. A straight bet covers one number and pays 35:1, while an even-money wager covers 18 numbers and pays 1:1. On the same wheel, those posted payouts leave the same long-run casino advantage for the standard bets shown by this calculator.
Will a roulette session lose exactly the displayed house edge?
No. The displayed house edge is a long-run average per unit wagered, not a prediction for a session or the next spin. Independent roulette spins can produce winning streaks, losing streaks, or results far from the expected average in the short run.
What does expected return per unit mean in this roulette calculator?
Expected return per unit is the average net result from repeatedly making the selected 1-unit roulette bet. For example, -0.0270 means an average long-run loss of 0.027 units for each unit staked, rather than a guaranteed loss on the next spin.
What roulette choice minimizes the standard house edge?
Among the standard European and American wheel options here, the European wheel has the lower house edge because it has one zero rather than zero and double zero. Bet selection still changes hit frequency and payout size, so choose it for the volatility you accept rather than expecting one standard bet to have a superior long-run price on the same wheel.
Roulette Arc Predictor mini-game
This optional roulette mini-game turns coverage differences into a visual challenge. Position the glowing prediction arc around the wheel and select an arc width representing a straight, corner, dozen, or even-money wager. Narrow arcs imitate high-payout roulette bets: they cover fewer pockets and are harder to hit. Wider arcs cover more pockets, connect more often, and use lower payouts. The wheel selector above is reused, so switching from European to American also changes the number of pockets in the game.
The Arc Predictor is separate from the calculator’s numerical result. It does not change the reported roulette probabilities, expected return, or house edge. It is simply a replayable illustration of coverage and volatility: aim with a mouse, touch, or keyboard; use buttons or keys 1 through 7 to change bet size; and try to score before the timer ends. Bonus rounds and increasing speed are game mechanics, not roulette strategy advice.
Tip: wider roulette coverage raises the chance of a hit, while narrow coverage creates higher-scoring but less frequent wins.
Educational note: the mini-game represents roulette coverage as one glowing arc. As in the calculator, win probability is covered pockets divided by total wheel pockets.
For a direct roulette comparison, calculate the selected wheel and wager first, then choose the matching wheel in the game. The American wheel’s extra pocket leaves less coverage relative to the total and produces the higher standard house edge.